Increasing Thermal Conductivity of Host Polymer Used With Laser Engraving Methods and Compositions

ABSTRACT

the invention provides a composition having laser engraving properties, comprising a host material and a laser enhancing additive. The host material comprises a material, such as a polymer, modified by a first process, whereby the host material as modified by the first process has increased thermal conductivity as compared to the host material before the first process. The laser enhancing additive comprises a first quantity of at least one of copper potassium iodide (CuKI 3 ), Copper Iodide (CuI), potassium iodide (KI), sodium iodide (NaI), and aluminum iodide (AlI), and a second quantity of at least one substance selected from the group consisting of zinc sulfide (ZnS), barium sulfide (BaS), alkyl sulfonate, and thioester.

CROSS REFERENCE TO RELATED APPLICATION

The present application is a continuation of Ser. No. 10/677,092, filedSep. 30, 2003, which is a continuation-in-part of Ser. No. 10/326,886,filed Dec. 20, 2002 and claims priority to 60/471,429, filed May 16,2003 and claims priority to 60/500,204, filed Sep. 3, 2003, and claimspriority to 60/504,352, filed Sep. 19, 2003, the contents of which areincorporated hereby by reference in their entirety:

RELATED APPLICATION DATA

The present application is related to U.S. patent application Ser. No.09/747,735, filed Dec. 22, 2000, 09/602,313, filed Jun. 23, 2000, and10/094,593, filed Mar. 6, 2002, U.S. Provisional Patent Application No.60/358,321, filed Feb. 19, 2002, as well as U.S. Pat. No. 6,066,594.Each of the above U.S. Patent documents is herein incorporated byreference. The present application also is related to the following U.S.patent application documents:

-   -   Systems, Compositions, and Methods for Full Color Laser        Engraving of ID Documents (application Ser. No. 10/330,034,        Attorney Docket No. P0734D, filed Dec. 24, 2002—Inventor Robert        Jones);    -   Laser Etched Security Features for Identification Documents and        Methods of Making Same (application Ser. No. 10/330,033,        Attorney Docket No. P0736D, filed Dec. 24, 2002—Inventors George        Theodossiou and Robert Jones);    -   Identification Document and Related Methods (Application No.        60/421,254, Attorney Docket No. P0703, Inventors: Geoff Rhoads,        et al);    -   Identification Document and Related Methods (Application No.        60/418,762, Attorney Docket No. P0696, Inventors: Geoff Rhoads,        et al);    -   Enhanced Shadow Reduction System and Related Technologies for        Digital Image Capture (Application No. 60/447,502, Attorney        Docket No. P0789D, filed Feb. 13, 2003—Inventors Scott D. Haigh,        Tuan A. Hoang, Charles R. Duggan, David Bohaker, and Leo M.        Kenen);    -   Enhanced Shadow Reduction System and Related Technologies for        Digital Image Capture (application Ser. No. 10/663,439, Attorney        Docket No. P0883D filed Sep. 15, 2003—Inventors Scott D. Haigh,        Tuan A. Hoang, Charles R. Duggan, David Bohaker, and Leo M.        Kenen);

TECHNICAL FIELD

The invention generally relates to methods and compositions for lasermarking or engraving that contain one or more laser enhancing additives,as well as methods for conveying information, images, and securityfeatures on data carriers through laser engraving and marking, includinglaser engraving and marking using such compositions. In particular, theinvention relates to techniques and methods for decreasing the markingspeeds of images using a laser for marking of ID documents by increasingthe thermal conductivity of the host polymer and its' interpenetratingnetwork (IPN).

BACKGROUND AND SUMMARY

Identification documents (hereafter “ID documents”) play a critical rolein today's society. One example of an ID document is an identificationcard (“ID card”). ID documents are used on a daily basis—to proveidentity, to verify age, to access a secure area, to evidence drivingprivileges, to cash a check, and so on. Airplane passengers are requiredto show an ID document during check in, security screening, and prior toboarding their flight. In addition, because we live in an ever-evolvingcashless society, ID documents are used to make payments, access an ATM,debit an account, or make a payment, etc.

Many types of identification cards and documents, such as drivinglicenses, national or government identification cards, bank cards,credit cards, controlled access cards and smart cards, carry thereoncertain items of information which relate to the identity of the bearer.Examples of such information include name, address, birth date,signature and photographic image; the cards or documents may in additioncarry other variant data (i.e., data specific to a particular card ordocument, for example an employee number) and invariant data (i.e., datacommon to a large number of cards, for example the name of an employer).AlI of the cards described above will hereinafter be genericallyreferred to as “ID documents”.

In the production of images useful in the field of identificationdocumentation, it is oftentimes desirable to embody into a document(such as an ID card, drivers license, passport or the like) data orindicia representative of the document issuer (e.g., an official seal,or the name or mark of a company or educational institution) and data orindicia representative of the document bearer (e.g., a photographiclikeness, name or address). Typically, a pattern, logo or otherdistinctive marking representative of the document issuer will serve asa means of verifying the authenticity, genuineness or valid issuance ofthe document. A photographic likeness or other data or indicia personalto the bearer will validate the right of access to certain facilities orthe prior authorization to engage in commercial transactions andactivities.

Identification documents, such as ID cards, having printed backgroundsecurity patterns, designs or logos and identification data personal tothe card bearer have been known and are described, for example, in U.S.Pat. No. 3,758,970, issued Sep. 18, 1973 to M. Annenberg; in GreatBritain Pat. No. 1,472,581, issued to G. A. O. Gesellschaft FurAutomation Und Organisation mbH, published Mar. 10, 1976; inInternational Patent Application PCT/GB82/00150, published Nov. 25, 1982as Publication No. WO 82/04149; in U.S. Pat. No. 4,653,775, issued Mar.31, 1987 to T. Raphael, et al.; in U.S. Pat. No. 4,738,949, issued Apr.19, 1988 to G. S. Sethi, et al.; and in U.S. Pat. No. 5,261,987, issuedNov. 16 1993 to J. W. Luening, et al. AlI of the aforementioneddocuments are hereby incorporated by reference.

The advent of commercial apparatus (printers) for producing dye imagesby thermal transfer has made relatively commonplace the production ofcolor prints from electronic data acquired by a video camera. Ingeneral, this is accomplished by the acquisition of digital imageinformation (electronic signals) representative of the red, green andblue content of an original, using color filters or other known means.These signals are then utilized to print an image onto a data carrier.For example, information can be printed using a printer having aplurality of small heating elements (e.g., pins) for imagewise heatingof each of a series of donor sheets (respectively, carrying sublimablecyan, magenta and yellow dye). The donor sheets are brought into contactwith an image-receiving element (which can, for example, be a substrate)which has a layer for receiving the dyes transferred imagewise from thedonor sheets. Thermal dye transfer methods as aforesaid are known anddescribed, for example, in U.S. Pat. No. 4,621,271, issued Nov. 4, 1986to S. Brownstein and U.S. Pat. No. 5,024,989, issued Jun. 18, 1991 to Y.H. Chiang, et al. Each of these patents is hereby incorporated byreference.

Commercial systems for issuing ID documents are of two main types,namely so-called “central” issue (CI), and so-called “on-the-spot” or“over-the-counter” (OTC) issue.

CI type ID documents are not immediately provided to the bearer, but arelater issued to the bearer from a central location. For example, in onetype of CI environment, a bearer reports to a document station wheredata is collected, the data are forwarded to a central location wherethe card is produced, and the card is forwarded to the bearer, often bymail. Another illustrative example of a CI assembling process occurs ina setting where a driver passes a driving test, but then receives herlicense in the mail from a CI facility a short time later. Still anotherillustrative example of a CI assembling process occurs in a settingwhere a driver renews her license by mail or over the Internet, thenreceives a drivers license card through the mail.

Centrally issued identification documents can be produced from digitallystored information and generally comprise an opaque core material (alsoreferred to as “substrate”), such as paper or plastic, sandwichedbetween two layers of clear plastic laminate, such as polyester, toprotect the aforementioned items of information from wear, exposure tothe elements and tampering. The materials used in such CI identificationdocuments can offer the ultimate in durability. In addition, centrallyissued digital identification documents generally offer a higher levelof security than OTC identification documents because they offer theability to pre-print the core of the central issue document withsecurity features such as “micro-printing”, ultra-violet securityfeatures, security indicia and other features currently unique tocentrally issued identification documents. Another security advantagewith centrally issued documents is that the security features and/orsecured materials used to make those features are centrally located,reducing the chances of loss or theft (as compared to having securedmaterials dispersed over a wide number of “on the spot” locations).

In addition, a CI assembling process can be more of a bulk processfacility, in which many cards are produced in a centralized facility,one after another. The CI facility may, for example, process thousandsof cards in a continuous manner. Because the processing occurs in bulk,CI can have an increase in efficiency as compared to some OTC processes,especially those OTC processes that run intermittently. Thus, CIprocesses can sometimes have a lower cost per ID document, if a largevolume of ID documents are manufactured.

In contrast to CI identification documents, OTC identification documentsare issued immediately to a bearer who is present at a document-issuingstation. An OTC assembling process provides an ID document“on-the-spot”. (An illustrative example of an OTC assembling process isa Department of Motor Vehicles (“DMV”) setting where a driver's licenseis issued to person, on the spot, after a successful exam.). In someinstances, the very nature of the OTC assembling process results insmall, sometimes compact, printing and card assemblers for printing theID document.

OTC identification documents of the types mentioned above can take anumber of forms, depending on cost and desired features. Some OTC IDdocuments comprise highly plasticized polyvinyl chloride (PVC) or have acomposite structure with polyester laminated to 0.5-2.0 mil (13-51.mu.m)PVC film, which provides a suitable receiving layer for heattransferable dyes which form a photographic image, together with anyvariant or invariant data required for the identification of the bearer.These data are subsequently protected to varying degrees by clear, thin(0.125-0.250 mil, 3-6.mu.m) overlay patches applied at the print head,holographic hot stamp foils (0.125-0.250 mil 3-6.mu.m), or a clearpolyester laminate (0.5-10 mil, 13-254.mu.m) supporting common securityfeatures. These last two types of protective foil or laminate sometimesare applied at a laminating station separate from the print head. Thechoice of laminate dictates the degree of durability and securityimparted to the system in protecting the image and other data.

FIGS. 1 and 2 illustrate a front view and cross-sectional view (takenalong the A-A line), respectively, of an exemplary prior artidentification (ID) document 10. In FIG. 1, the prior art ID document 1includes a photographic image 12, a bar code 14 (which may containinformation specific to the person whose image appears in photographicimage 12 and/or information that is the same from ID document to IDdocument), variable personal information 16, such as an address,signature, and/or birthdate, and biometric information 18 associatedwith the person whose image appears in photographic image 12 (e.g., afingerprint). Although not illustrated in FIG. 1, the ID document 10 caninclude a magnetic stripe (which, for example, can be on the rear side(not shown) of the ID document 10), and various security features, suchas a security pattern (for example, a printed pattern comprising atightly printed pattern of finely divided printed and unprinted areas inclose proximity to each other, such as a fine-line printed securitypattern as is used in the printing of banknote paper, stockcertificates, and the like).

Referring to FIG. 2, the ID document 10 comprises a pre-printed core 20(such as, for example, white PVC material) that is, for example, about25 mil thick. The core 20 is laminated with a transparent material, suchas clear PVC material 22, which, by way of example, can be about 1-5 milthick. The composite of the core 20 and clear PVC material 22 form aso-called “card blank” 25 that can be up to about 30 mils thick.Information 26 a-c is printed on the card blank 25 using a method suchas Dye Diffusion Thermal Transfer (“D2T2”) printing (described furtherin commonly assigned U.S. Pat. No. 6,066,594, which is incorporatedhereto by reference in its entirety.) The information 26 a-c can, forexample, comprise an indicium or indicia, such as the invariant ornonvarying information common to a large number of identificationdocuments, for example the name and logo of the organization issuing thedocuments. The information 26 a-c may be formed by any known processcapable of forming the indicium on the specific core material used.

To protect the information 26 a-c that is printed, an additional layerof overlaminate 24 can be coupled to the card blank 25 and printing 26a-c using, for example, 1 mil of adhesive (not shown). The overlaminate24 can be substantially transparent. Materials suitable for forming suchprotective layers are known to those skilled in the art of makingidentification documents and any of the conventional materials may beused provided they have sufficient transparency. Examples of usablematerials for overlaminates include biaxially oriented polyester orother optically clear durable plastic film.

The above-described printing techniques are not the only methods forprinting information on data carriers such as ID documents. Laser beams,for example can be used for marking, writing, bar coding, and engravingmany different types of materials, including plastics. Lasers have beenused, for example, to mark plastic materials to create indicia such asbar codes, date codes, part numbers, batch codes, and company logos. Itwill be appreciated that laser engraving or marking generally involves aprocess of inscribing or engraving a document surface withidentification marks, characters, text, tactile marks—including text,patterns, designs (such as decorative or security features),photographs, etc.

One way to laser mark thermoplastic materials involves irradiating amaterial, such as a thermoplastic, with a laser beam at a givenradiation. The area irradiated by the laser absorbs the laser energy andproduces heat which causes a visible discoloration in the thermoplastic.The visible discoloration serves as a “mark” or indicator; it will beappreciated that laser beams can be controlled to form patterns of“marks” that can form images, lines, numbers, letters, patterns, and thelike. Depending on the type of laser and the type of material used,various types of marks (e.g., dark marks on light backgrounds, lightmarks on dark backgrounds, colored marks) can be produced. Some types ofthermoplastics, such as polyvinylchloride (PVC), acrylonitrile butadienestyrene (ABS), and polyethylene terephthalate (PET), are capable ofabsorbing laser energy in their native states. Some materials which aretransparent to laser energy in their native state, such as polyethylene,may require the addition of one or more additives to be responsive tolaser energy.

For additional background, various laser marking and/or engravingtechniques are disclosed, e.g., in U.S. Pat. Nos. 6,022,905, 5,298,922,5,294,774, 5,215,864 and 4,732,410. Each of these patents is hereinincorporated by reference. In addition, U.S. Pat. Nos. 4,816,372,4,894,110, 5,005,872, 5,977,514, and 6179338 describe variousimplementations for using a laser to print information, and thesepatents are incorporated herein in their entirety.

Using laser beams to write or engrave information to ID cards presents anumber of advantages over conventional printing. For example, thefoaming of the thermoplastic that can occur with some types of laserengraving can be adapted to provide an indicium having a tactile feel,which is a useful authenticator of a data carrier that also can be verydifficult to counterfeit or alter. In addition, laser engravinggenerally does not require the use of ink, which can reduce the cost ofconsumables used to manufacture an ID card. Laser engraving can also bemore durable than ink printing, and more resistant to abrasion (whichcan be particularly useful if a counterfeiter attempts to “rub off” anindicium on an ID card). The resolution and print quality of laserengraving often can be higher than that of conventional ink-basedprinting. Laser engraving also can be a more environmentally friendlymanufacturing process than printing with ink, especially becausesolvents and other chemicals often used with ink generally are not usedwith laser engraving.

Despite the advantages of laser engraving, certain limitations stillexist. Even when using known laser-enhancing additives, laser marking ofsome types of materials does not produce an adequate contrast for allapplications. Some types of materials, such as silica filled polyolefin,TESLIN core ID documents and TESLIN composite structures (TESLIN isavailable from PPG Industries, Inc., Pittsburgh, Pa.) using conventionalover-laminate materials, are not easily laser engraved. Further, evenwith use of known laser additives, laser engraving can take too muchtime and/or too much laser energy to be useful in some manufacturingenvironments.

Another limitation of laser engraving has been marking speeds. Theability to mark a rastered image via a laser such as a diode pumped YAGlaser requires understanding of at least three primary components:materials (e.g., card or other substrate), image information, and laserconditions. AlI three can work together to determine the speed at whichan acceptable mark is made via laser engraving/marking. Depending on thespeed required and the volume of documents to be made, a certain numberof lasers will be needed to engrave the documents. Laser engravingmachines are quite costly at present, and despite various improvementsmade to laser engraving machines to increase speed, laser engravingdocuments at an acceptable speed and throughput and image qualitycontinues to require, in many instances, multiple laser engravingmachines. We have found, however, that by making certain changes to thematerials being engraved (which changes are described further herein),it is possible to decrease the time required for laser engraving/markingof images. Decreasing this marking speed can help to increase throughputand may help to reduce the number of laser engraving machines that arerequired.

In one aspect, we have found that laser engraving of some types ofmaterials, including materials that are not easily engraved (such aslaminated TESLIN core ID documents), can be improved by increasing thesensitivity to laser radiation of a laminate used with the materialand/or increasing the sensitivity to laser radiation of a coatingapplied to the material.

One inventive technique disclosed herein improves the material beinglaser marked or laser engraved by introducing inventive laser enhancingadditives to the material. The material can be a laminate, a coating, anarticle having a laminate or coating formed thereon, and even an imagereceiving layer/image capable layer that is used for receiving imagesprinted in a manner such as D2T2, laser xerography, inkjet, and masstransfer printing. Components of the laser enhancing additive describedherein also can be added, alone or combined with other components, to aseries of materials having a laser-receptive optical path between them,to enhance the laser engraving of at least one material in the series.These additives facilitate material sensitivity, greatly improving theability to laser engrave laminated ID documents. In some embodiments,these additives can also improve the performance of laser engraving evenon even those structures (e.g., fused polycarbonate card structures,polyvinylchloride (PVC), polyethylene terephthalate (PET), andacrylonitrile butadiene styrene (ABS)) that can tend to be more easilyengraved by laser energy.

The inventors have found that by using the inventive additives describedherein, the processing time for polycarbonate and other ID cardstructures may be decreased. In addition, user of the laser enhancingadditives described herein may enable laser engraving to be accomplishedusing less laser energy and/or lower levels of laser energy than inknown methods. Another inventive technique disclosed herein improves thesensitivity of a material being laser engraved by applying a coating tothe material, the coating containing at least one laser enhancingadditive as described below. The material can be part of virtually anytype of article to be laser marked or laser engraved. For example, inone embodiment the material is a core layer in an identificationdocument.

In one embodiment, the additive used to enhance laser engravingcomprises a mixture of at least one of copper potassium iodide (CuKI₃)or Copper Iodide (CuI) or potassium iodide (KI) or sodium iodide (NaI)or aluminum iodide (AlI) along with at least one substance selected fromthe group consisting of zinc sulfide (ZnS), barium sulfide (BaS), alkylsulfonate (e.g., RSO₂Na or R—OSO₂Na), and Thioester (e.g., substancescontaining —SH). This additive can be added to a laminate layer (wherethe laminate layer itself is to be laser engraved or marked) and/or to acoating (where the surface being coated is to be laser engraved ormarked).

Advantageously, in one embodiment, the additive comprises an effectiveamount of copper iodide, potassium iodide, sodium iodide, aluminumiodide, and zinc sulfide in a host material. The host material can, forexample, be a laminate or a coating. The host material also can beanother material that is later added to a laminate or coating. The hostmaterial can, for example, be a thermoplastic or thermoset. The hostmaterial can be a material added or applied to another material to makethat material more receptive to another type of printing or marking(e.g., an image receiving layer, such as is disclosed in commonlyassigned U.S. Pat. No. 6,066,594, the contents of which are herebyincorporated by reference).

In another advantageous embodiment, the additive comprises an effectiveamount of any combination thereof of copper iodide, potassium iodide,sodium iodide, aluminum iodide, zinc sulfide, barium sulfide (BaS),alkyl sulfonate (e.g., RSO₂Na or R—OSO₂Na), and Thioester (e.g.,substances containing —SH), in a host material. The host material can,for example, be a laminate or a coating. The host material also can beanother material that is later added to a laminate or coating. The hostmaterial can, for example, be a thermoplastic or thermoset. The hostmaterial can be a material added or applied to another material to makethat material more receptive to another type of printing or marking(e.g., an image receiving layer, such as is disclosed in commonlyassigned U.S. Pat. No. 6,066,594, the contents of which are herebyincorporated by reference).

For laminates, the host material (as well as the laminate to which thehost material may be added) generally can be any material whose laserengraving/marking properties are improved by the addition of the laserenhancing additive described herein, and it is expected that manymaterials developed in the future will be able to make use of theadditive described herein. In at least one embodiment, the addition ofthe laser enhancing additive described herein enables the laminate to belaser engraved with a grayscale image. In another aspect of theinvention, described further herein, we have found that for hostmaterials that are polymers, improving the thermal conductivity of thehost material and/or its interpenetrating network (IPN) (e.g., matrices)can help to decrease marking time for laser marking/engraving of images.

In at least one embodiment, the laminate containing the inventive laserenhancing additive can be applied to a layer of material and, afterapplication of heat and pressure to the laminate (e.g., via a platenpress), the laminate can comingle with the layer of material enough toactually improve the laser engraving properties of the layer of materialthat was laminated.

For coatings, in one embodiment, the additive comprises an effectiveamount of copper potassium iodide and zinc sulfide in a liquid carriermaterial, which together form a coating that can be applied to anarticle to be laser engraved. The liquid carrier material can bevirtually any known material that can be used as a coating, includingresins, polyesters, polycarbonates, vinyls, acrylates, urethanes, andcellulose-base coating. In one embodiment, the liquid carrier materialis a material used for coating a surface of a core material (e.g.,TESLIN, polycarbonate) of an identification document. The surface beingcoated generally can be any material (including laminates) whose laserengraving properties are improved by the addition of a coatingcontaining the laser enhancing additive described herein. In at leastone embodiment, the addition of the inventive additive to a coatingenables the surface to be capable of being engraved with a grayscaleimage.

For coatings, in another embodiment, the additive comprises an effectiveamount of at least one of Copper Iodide (CuI), potassium iodide (KI),sodium iodide (NaI), aluminum iodide (AlI), copper potassium iodide,zinc sulfide, and any combination thereof, in a liquid carrier material,which together form a coating that can be applied to an article to belaser engraved. The liquid carrier material can be virtually any knownmaterial that can be used as a coating, including resins, polyesters,polycarbonates, vinyls, acrylates, urethanes, and cellulose-basecoating. In one embodiment, the liquid carrier material is a materialused for coating a surface of a core material (e.g., TESLIN,polycarbonate) of an identification document. The surface being coatedgenerally can be any material (including laminates) whose laserengraving properties are improved by the addition of a coatingcontaining the laser enhancing additive described herein. In at leastone embodiment, the addition of the inventive additive to a coatingenables the surface to be capable of being engraved with a grayscaleimage.

In at least one embodiment, the coating containing the inventive laserenhancing laminate can be applied to a layer of material and, afterapplication of heat and pressure to the coating (e.g., via a platenpress), the coating can comingle with the layer of material enough toactually improve the laser engraving properties of the layer of materialthat was coated.

For transparent laminates and/or coatings, the effective amount of thelaser enhancing additive can vary depending on the tolerance forpossible reduction in the transparency of the laminate or coating. Inone embodiment, for transparent laminates or coating, the effectiveamount of the additive can range from 0.001% by weight up to about 0.1%by weight (based on the total weight of the material to which theadditive is added.).

For non-transparent laminates and/or coatings (e.g. colored coatings,colored laminates and/or opaque laminates), the effective amount of theadditive can be higher than 1% (e.g., 1%-100%). Those skilled in the artwill recognize that the effective amount of the additive for a given usecan depend on a number of factors, including the properties of thelaminate or coating, the type of laser engraving being performed (e.g.,grayscale or non-grayscale), the type of laser used, the desiredproperties or features of the article or surface being engraved, etc.Advantageously, for at least some transparent laminates and/or coatingsused in forming identification documents, the effective amount of theadditive is about 0.06% by weight.

In another advantageous embodiment, the constituents of theabove-described additive can be present in one or more different layersthrough which a laser beam can pass. In one example, the copperpotassium iodide (or copper Iodide (CuI) or potassium iodide (KI) orsodium iodide (NaI), aluminum iodide (AlI) and any combination thereof)can be present in a first layer of laminate and the zinc sulfide (orbarium sulfide (BaS), alkyl sulfonate (e.g., RSO₂Na or R—OSO₂Na),Thioester (e.g., substances containing —SH) and combinations thereof)can be present in a second layer of laminate, where the first and secondlayers are either adjacent or separated by one or more layers ofmaterial (e.g., another laminate or an adhesive) that is transparent tolaser radiation. When a laser beam is directed such that it passesthrough both of the layers, the combined action of the copper potassiumiodide and zinc sulfide enable laser engraving to occur in either orboth of the layers. In another example, an effective amount of copperpotassium iodide can be present in a coating applied to an article andan effective amount of zinc sulfide can be present in a laminate appliedover the coating.

In another example, each of the constituents of the inventive laserenhancing additive (e.g., copper, potassium, iodine, etc.) can bepresent in a separate layer of coating and/or laminate, where therespective layers are either adjacent or separated by one or more layersof material (e.g., another laminate or an adhesive) that is transparentto laser radiation. When a laser beam is directed such that it passesthrough all of the layers containing a constituent of the inventivelaser enhancing additive, the combined action of the constituents enablelaser engraving to occur in at least one of the respective layers. Theconstituents also can be combined with one or more other constituents,in different layers, in this manner. For example, an effective amount ofcopper iodide and sodium iodide can be present in a coating applied toan article and an effective amount of zinc sulfide and potassium iodidecan be present in a laminate applied over the coating, and an effectiveamount of aluminum iodide can be present in a coating that is thenapplied over that laminate. This example is not, of course, limiting;those skilled in the art will appreciate that there are many differentways to combine and/or separate the constituents of the inventive laserenhancing additive into one or more layers of coatings and/or laminates.

In another aspect, the invention provides a composition having laserengraving properties, comprising a host material and an effective amountof a laser enhancing additive.

The laser enhancing additive comprises a first quantity of least one of:copper potassium iodide (CuKI₃), Copper Iodide (CuI), potassium iodide(KI), sodium iodide (NaI), aluminum iodide (AlI), and any combinationthereof, and a second quantity of at least one substance selected fromthe group consisting of zinc sulfide (ZnS), barium sulfide (BaS), alkylsulfonate, and thioester, and any combination thereof. In oneembodiment, the first and second quantities are the same (for example,one part copper iodide and one part barium sulfide). In one embodiment,the first and second quantities are different (for example, three partspotassium iodide to one part zinc sulfide, or 2 parts copper iodide to 4parts thioester). In one embodiment, the composition is markable by atleast one of an excimer, Nd:YAG, and C0₂ laser (including both lightpumped and diode pumped Nd:YAG lasers).

In one embodiment, the laser enhancing additive is present in thecomposition in an amount from about 0.001 to 0.100 percent by weightbased on the total weight of the composition. In one embodiment, thelaser enhancing additive is present in an amount between 0.1 percent and100 percent by weight based on the total weight of the composition. Inone embodiment, the laser enhancing additive is present in an amountthat is about 0.06 percent by weight based on the total weight of thecomposition. In one embodiment, the laser enhancing additive comprises0.03 percent by weight of at least one of copper potassium iodide(CuKI₃), Copper Iodide (CuI), Potassium Iodide (KI), Sodium Iodide(NaI), Aluminum Iodide (AlI) and any combination thereof, and 0.03percent by weight of at least one of zinc sulfide (ZnS), barium sulfide(BaS), alkyl sulfonate, and thioester, or any combination thereof, eachweight based on the total weight of the composition.

In one embodiment, the host material of the composition is be a materialthat is not sensitive and/or transparent to laser radiation, such as amaterial that, by itself, is unable to have acceptable gray scale imageslaser engraved onto it. The host material can be a laminate or acoating. For example, the host material can comprise at least one of athermosetting material, thermoplastic, polymer, copolymer,polycarbonate, fused polycarbonate, polyester, amorphous polyester,polyolefin, silicon-filled polyolefin, TESLIN, foamed polypropylenefilm, polyvinyl chloride, polyethylene, thermoplastic resins,engineering thermoplastic, polyurethane, polyamide, polystyrene,expanded polypropylene, polypropylene, acrylonitrile butadiene styrene(ABS), ABS/PC, high impact polystyrene, polyethylene, polyethyleneterephthalate (PET), PET-G, PET-F, polybutylene terephthalate PBT),acetal copolymer (POM), polyetherimide (PEI), polyacrylate,poly(4-vinylpyridine, poly(vinyl acetate), polyacrylonitrile, polymericliquid crystal resin, polysulfone, polyether nitride, andpolycaprolactone, and combinations thereof. In one advantageousembodiment, it has been found that selecting host materials withrelatively high degrees of crystallinity (e.g., PET) can help to improvethe thermal conductivity of the resultant host material when theinventive laser enhancing additive is added to it.

We have further discovered other techniques for improving thermalconductivity of the host material to improve laser engraving efficiency.In one embodiment, the host material comprises a material havingcross-linked functionality. In one embodiment, the host material furthercomprises a second element, such as a transparent, conductive polymer,such as a cross-linked moiety such as polyurethane, glass beads, glassfibers, and CR-39 (a highly cross-linked thermoset prepared bypolymerization of diethylene glycol bis(allyl carbonate) monomer,available from PPG Industries). In one advantageous embodiment, a verylow concentration of the second element is blended with the hostmaterial. In one advantageous embodiment, the host material comprises atleast one of glass beads, glass fibers, and glass threads along with across-linking agent.

In one embodiment, the thermal conductivity of the host material ischanged by processing the host material to change its orientation and/ordensity. Those skilled in the art will be familiar with the varioustypes of processes and operations that can operate to change orientationand/or density of a host material.

In at least one embodiment, the invention provides an article ofmanufacture (such as an identification document) capable of being laserengraved with a grayscale image, comprising a core layer, a first layerand a second layer. The core layer has a first surface. The first layercomprises a first host material, the first host material comprising aneffective amount of a first laser enhancing additive comprising at leastone of one of copper potassium iodide (CuKI₃), Copper Iodide (CuI),Potassium Iodide (KI), Sodium Iodide (NaI), Aluminum Iodide (AlI) andany combination thereof. The second layer comprises a second hostmaterial and is oriented in relation to the first host material suchthat a single laser beam can penetrate both at least a portion of thefirst layer and at least a portion of the second layer. The second hostmaterial comprises an effective amount of at least one second laserenhancing additive selected from the group consisting of zinc sulfide(ZnS), barium sulfide (BaS), alkyl sulfonate, and thioester, and anycombinations thereof. The first and second layers are operably coupledto each other and at least one of the first and second layers isoperably coupled to the first surface of the core layer. In oneembodiment, a grayscale image is laser engraved into at least one of thefirst and second layers.

In one embodiment, first layer is substantially transparent and thefirst laser enhancing additive is present in an amount from about 0.001to 0.100 percent by weight based on the total weight of the first hostmaterial. In one embodiment, the second layer is substantiallytransparent, and the second laser enhancing additive is present in anamount from about 0.001 to 0.100 percent by weight based on the totalweight of the second host material. In one embodiment, a third layer isdisposed between the first and second layers; the third layer comprisesa material that permits transmission of a laser beam therethrough.

In another aspect, the invention provides a method of engraving amaterial by exposing the material to laser radiation. An effectiveamount of a laser enhancing additive is added to the material. The laserenhancing additive comprises at least one of copper potassium iodide(CuKI₃), Copper Iodide (CuI), Potassium Iodide (KI), Sodium Iodide(NaI), Aluminum Iodide (AlI) and any combination thereof, and at leastone substance selected from the group consisting of zinc sulfide (ZnS),barium sulfide (BaS), alkyl sulfonate, and thioester, and anycombinations thereof. The material is exposed to laser radiation in amanner that causes the material to be engraved by the laser radiation.In one embodiment, the effective amount of the laser enhancing additivecomprises 0.01% to 0.1% by weight of the material, e.g. 0.06% by weight.In one embodiment, the effective amount of the laser enhancing additivecomprises 0.1% to 100% by weight of the material. In one embodiment, anindicium is formed in grayscale in at least a portion of the materialthrough the exposure of the portion of the material to laser radiation.In one embodiment, the laser engraved material is used in themanufacture of an identification document.

In another embodiment, the invention provides a method of laserengraving a grayscale image on an article having first and secondlayers. A first effective amount of least one of copper potassium iodide(CuKI₃), Copper Iodide (CuI), Potassium Iodide (KI), Sodium Iodide(NaI), Aluminum Iodide (AlI) and any combination thereof, is added tothe first layer. A second effective amount of at least one substanceselected from the group consisting of zinc sulfide (ZnS), barium sulfide(BaS), alkyl sulfonate, and thioester, and any combination thereof, isadded to the second layer. A laser beam, such as a beam from at leastone of an Nd:Yag laser and a CO₂ laser, is directed so that it passesthrough at least a portion of the first layer and at least a portion ofthe second layer to form a grayscale image in at least one of the firstand second layers. In one embodiment, the laser beam is directed so thatit that it passes through at least a portion of the first layer and atleast a portion of the second layer such that the first and secondlayers become affixed to each other.

In at least one embodiment, the invention provides a multilayeridentification document, comprising a core layer and a film layer. Thefilm layer overlays at least a portion of the core layer and is affixedto the portion of the core layer. The film layer comprising an additivethat comprises an effective amount of least one of copper potassiumiodide (CuKI₃), Copper Iodide (CuI),), Potassium Iodide (KI), SodiumIodide (NaI), Aluminum Iodide (AlI) and any combination thereof, and aneffective amount of at least one substance selected from the groupconsisting of zinc sulfide (ZnS), barium sulfide (BaS), alkyl sulfonate,and thioester, and any combination thereof. In one embodiment, theidentification document bears a first indicium thereon, the indiciaobtained by exposing the film layer to a laser beam. In one embodiment,the indicia comprises at least one of a gray scale image, photograph,text, tactile text, graphics, information, security pattern, securityindicia, and a digital watermark.

In another aspect, the invention provides an identification documenthaving improved laser engraving characteristics. The identificationdocument comprises a TESLIN core coated with a coating containing thelaser enhancing additive described above. A grayscale image representingvariable data (e.g., personalized data) is laser engraved onto theTESLIN core using an Nd:YAG laser. Optionally, a laminate can be affixedto the TESLIN either before laser engraving or after laser engraving. Ifthe laminate is applied before the TESLIN core is laser engraved, thelaminate generally will be transparent to laser radiation.

In one embodiment, the invention provides a composition having laserengraving properties, comprising a host material and a laser enhancingadditive. The host material comprises a material, such as a polymer,modified by a first process, whereby the host material as modified bythe first process has increased thermal conductivity as compared to thehost material before the first process. The laser enhancing additivecomprises a first quantity of at least one of copper potassium iodide(CuKI₃), Copper Iodide (CuI), potassium iodide (KI), sodium iodide(NaI), and aluminum iodide (AlI), and a second quantity of at least onesubstance selected from the group consisting of zinc sulfide (ZnS),barium sulfide (BaS), alkyl sulfonate, and thioester.

In another embodiment, the invention provides an article of manufacture,such as an identification document, capable of being laser engraved witha grayscale image, comprising a core layer, a first layer, and a secondlayer. The core layer has a first surface. The first layer comprises afirst host material, the first host material comprising a materialmodified by a first process, whereby the host material as modified bythe first process has increased thermal conductivity as compared to thehost material before the first process, the host material furthercomprising an effective amount of a first laser enhancing additivecomprising at least one of one of copper potassium iodide (CuKI₃),Copper Iodide (CuI), potassium iodide (KI), sodium iodide (NaI), andaluminum iodide (AI). The second layer comprises a second host material,the second layer being oriented in relation to the first host materialsuch that a single laser beam can penetrate both at least a portion ofthe first layer and at least a portion of the second layer. The secondhost material comprises an effective amount of a second laser enhancingadditive, the second laser enhancing additive selected from the groupconsisting of zinc sulfide (ZnS), barium sulfide (BaS), alkyl sulfonate,and thioester. The first and second layers are operably coupled to eachother and at least one of the first and second layers is operablycoupled to the first surface of the core layer.

In one embodiment, the first process comprises at least one of addingcross linked functionality to the host material, adding a conductivematerial to the host material, the conductive material being a materialthat is more thermally conductive than the host material, altering atleast a portion of the free volume of the host material, and processingthe host material to change at least one of its orientation and density.

In another embodiment, the invention provides a method of engraving ahost material by exposing the material to laser radiation. A hostmaterial is provided, and a process is performed on the host materialsuch as at least one of adding cross linked functionality to the hostmaterial, adding a conductive material to the host material, theconductive material being a material that is more thermally conductivethan the host material, altering at least a portion of the free volumeof the host material, and processing the host material to change atleast one of its orientation and density, to increase the thermalconductivity of the host material. An effective amount of a laserenhancing additive is added to the host material, the laser enhancingadditive comprising at least one of copper potassium iodide (CuKI₃),Copper Iodide (CuI), potassium iodide (KI), sodium iodide (NaI), andaluminum iodide (AI); and at least one substance selected from the groupconsisting of zinc sulfide (ZnS), barium sulfide (BaS), alkyl sulfonate,and thioester. The host material is exposed to laser radiation in amanner that causes the material to be engraved by the laser radiation.

Although some companies offer laser engraving document materials, suchmaterials and/or the amount of equipment required to laser engrave suchmaterials (especially for high quality grayscale images onidentification documents) can be prohibitively expensive. At least someembodiments of our invention can overcome at least some of these andother limitations of the prior art. At least some embodiments of ourinvention offer a less expensive option for laser engraving withimproved grayscale engraving, and ease of manufacture, without giving updesired security features.

The foregoing and other features and advantages of the present inventionwill be even more readily apparent from the following DetailedDescription, which proceeds with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The advantages, features, and aspects of embodiments of the inventionwill be more fully understood in conjunction with the following detaileddescription and accompanying drawings, wherein:

FIG. 1 is an illustrative example of a prior art identificationdocument;

FIG. 2 is an illustrative cross section of the prior art identificationdocument of FIG. 1, taken along the A-A line;

FIG. 3 is an illustrative cross-sectional view of an identificationdocument in accordance with a first embodiment of a first aspect of theinvention;

FIG. 4 is an illustrative cross sectional view of an identificationdocument in accordance with a second embodiment of the first aspect ofthe invention;

FIG. 5 is an illustrative cross sectional view of an identificationdocument in accordance with a third embodiment of the first aspect ofthe invention;

FIG. 6 is an illustrative cross sectional view of an identificationdocument in accordance with a fourth embodiment of the first aspect ofthe invention;

FIG. 7 is an illustrative cross sectional view of an identificationdocument in accordance with a first embodiment of a second aspect of theinvention;

FIG. 8 is an illustrative cross sectional view of an identificationdocument in accordance with a second embodiment of the second aspect ofthe invention;

FIGS. 9A-9B are an analytical graph and test data, respectively, from achemical analysis of a first laser enhancing additive used with oneembodiment of the invention;

FIGS. 10A-10B are an analytical graph and test data, respectively, froma chemical analysis of a second laser enhancing additive used with oneembodiment of the invention;

FIGS. 11A-11B are an analytical graph and test data, respectively, froma chemical analysis of a third laser enhancing additive used with oneembodiment of the invention;

FIGS. 12A-12B are an analytical graph and test data, respectively, froma chemical analysis of a fourth laser enhancing additive used with oneembodiment of the invention; and

FIGS. 13A-13B are an analytical graph and test data, respectively, froma chemical analysis of a fifth laser enhancing additive used with oneembodiment of the invention;

The drawings are not necessarily to scale, emphasis instead generallybeing placed upon illustrating the principles of the invention. Inaddition, in the figures, like numbers refer to like elements. Relativedimensions of identification documents, laminate layers, indicia, etc.,are provided for illustrative purposes only and are not limiting.Further, throughout this application, laser engraved indicia,information, identification documents, data, etc., may be shown ashaving a particular cross sectional shape (e.g., rectangular) but thatis provided by way of example and illustration only and is not limiting,nor is the shape intended to represent the actual resultant crosssectional shape that occurs during laser engraving or manufacturing ofidentification documents.

DETAILED DESCRIPTION A. Introduction and Definitions

In the foregoing discussion, the use of the word “ID document” isbroadly defined and intended to include at least all types of IDdocuments, including (but are not limited to), documents, magneticdisks, credit cards, bank cards, phone cards, stored value cards,prepaid cards, smart cards (e.g., cards that include one moresemiconductor chips, such as memory devices, microprocessors, andmicrocontrollers), contact cards, contactless cards, proximity cards(e.g., radio frequency (RFID) cards), passports, driver's licenses,network access cards, employee badges, debit cards, security cards,visas, immigration documentation, national ID cards, citizenship cards,social security cards and badges, certificates, identification cards ordocuments, voter registration and/or identification cards, police IDcards, border crossing cards, security clearance badges and cards, gunpermits, badges, gift certificates or cards, membership cards or badges,tags, CD's, consumer products, knobs, keyboards, electronic components,etc., or any other suitable items or articles that may recordinformation, images, and/or other data, which may be associated with afunction and/or an object or other entity to be identified.

Note that, for the purposes of this disclosure, the terms “document,”“card,” “badge” and “documentation” are used interchangeably.

In addition, in the foregoing discussion, “identification” includes (butis not limited to) information, decoration, and any other purpose forwhich an indicia can be placed upon an article in the article's raw,partially prepared, or final state. Also, instead of ID documents, theinventive techniques can be employed with product tags, productpackaging, business cards, bags, charts, maps, labels, etc., etc.,particularly those items including engraving of an laminate orover-laminate structure. The term ID document thus is broadly definedherein to include these tags, labels, packaging, cards, etc.

“Personalization”, “Personalized data” and “variable” data are usedinterchangeably herein, and refer at least to data, images, andinformation that are printed at the time of card personalization.Personalized data can, for example, be “personal to” or “specific to” aspecific cardholder or group of cardholders. Personalized data caninclude data that is unique to a specific cardholder (such as biometricinformation, image information), but is not limited to unique data.Personalized data can include some data, such as birthdate, height,weight, eye color, address, etc., that are personal to a specificcardholder but not necessarily unique to that cardholder (i.e., othercardholders might share the same personal data, such as birthdate).Depending on the application, however, personalized data can alsoinclude some types of data that are not different from card to card, butthat are still provided at the time of card personalization. Forexample, a state seal that is laser engraved onto a portion of anoverlaminate in an identification document, where the laser engravingoccurs during the personalization of the card, could in some instancesbe considered to be “personalized” information.

The terms “laser engraving” and “laser marking” are used interchangeablyherein.

The terms “indicium” and indicia as used herein cover not only markingssuitable for human reading, but also markings intended for machinereading. Especially when intended for machine reading, such an indiciumneed not be visible to the human eye, but may be in the form of amarking visible only under infra-red, ultra-violet or other non-visibleradiation. Thus, in at least some embodiments of the invention, anindicium formed on any layer in an identification document (e.g., thecore layer) may be partially or wholly in the form of a marking visibleonly under non-visible radiation. Markings comprising, for example, avisible “dummy” image superposed over a non-visible “real” imageintended to be machine read may also be used.

“Laminate” and “overlaminate” include (but are not limited to) film andsheet products. Laminates usable with at least some embodiments of theinvention include those which contain substantially transparent polymersand/or substantially transparent adhesives, or which have substantiallytransparent polymers and/or substantially transparent adhesives as apart of their structure, e.g., as an extruded feature. Examples ofusable laminates include at least polyester, polycarbonate, polystyrene,cellulose ester, polyolefin, polysulfone, or polyamide. Laminates can bemade using either an amorphous or biaxially oriented polymer as well.The laminate can comprise a plurality of separate laminate layers, forexample a boundary layer and/or a film layer.

The degree of transparency of the laminate can, for example, be dictatedby the information contained within the identification document, theparticular colors and/or security features used, etc. The thickness ofthe laminate layers is not critical, although in some embodiments it maybe preferred that the thickness of a laminate layer be about 1-20 mils.Lamination of any laminate layer(s) to any other layer of material(e.g., a core layer) can be accomplished using any conventionallamination process, and such processes are will-known to those skilledin the production of articles such as identification documents. Ofcourse, the types and structures of the laminates described herein areprovided only by way of example, those skilled in the art willappreciated that many different types of laminates are usable inaccordance with the invention.

For example, in ID documents, a laminate can provide a protectivecovering for the printed substrates and provides a level of protectionagainst unauthorized tampering (e.g., a laminate would have to beremoved to alter the printed information and then subsequently replacedafter the alteration.). Various lamination processes are disclosed inassignee's U.S. Pat. Nos. 5,783,024, 6,007,660, 6,066,594, and6,159,327. Other lamination processes are disclosed, e.g., in U.S. Pat.Nos. 6,283,188 and 6,003,581. Each of these U.S. patents is hereinincorporated by reference.

The material(s) from which a laminate is made may be transparent, butneed not be. Laminates can include synthetic resin-impregnated or coatedbase materials composed of successive layers of material, bondedtogether via heat, pressure, and/or adhesive. Laminates also includessecurity laminates, such as a transparent laminate material withproprietary security technology features and processes, which protectsdocuments of value from counterfeiting, data alteration, photosubstitution, duplication (including color photocopying), and simulationby use of materials and technologies that are commonly available.Laminates also can include thermosetting materials, such as epoxy.

For purposes of illustration, the following description will proceedwith reference to ID document structures (e.g., TESLIN-core,multi-layered ID documents) and fused polycarbonate structures. Itshould be appreciated, however, that the present invention is not solimited. Indeed, as those skilled in the art will appreciate, theinventive techniques can be applied to many other structures formed inmany different ways to improve their laser engraving characteristics.Generally, the invention has applicability for virtually any productwhich is to be laser engraved, especially products being engraved withgrayscale images. For example, in at least some embodiments, theinvention is usable with virtually any product which is to be laserengraved or marked, especially articles to which a laminate and/orcoating is applied, including articles formed from paper, wood,cardboard, paperboard, glass, metal, plastic, fabric, ceramic, rubber,along with many man-made materials, such as microporous materials,single phase materials, two phase materials, coated paper, syntheticpaper (e.g., TYVEC, manufactured by Dupont Corp of Wilmington, Del.),foamed polypropylene film (including calcium carbonate foamedpolypropylene film), plastic, polyolefin, polyester,polyethylenetelphthalate (PET), PET-G, PET-F, and polyvinyl chloride(PVC), and combinations thereof.

In addition, at least one embodiment of the invention relates tovirtually any article formed from, laminated with, or at least partiallycovered by a material that not sufficiently responsive to laserradiation to form a desired indicium (e.g., a grayscale image) thereon,but which is rendered more responsive to laser radiation, at least to asufficient degree to enable its surface to be marked as desired with alaser beam, by adding the inventive laser enhancing additive to thematerial itself or to another material (e.g., a coating or laminate)that is substantially adjacent to the material.

B. Laser Engraving

It is often desirable to mark a portion of a structure, such as amulti-layered structure (including after lamination), such as an IDdocument, with text, information, graphics, logos, security indicia,security features, marks, images and/or photographs. It would beadvantageous if techniques were available to enable laser engraving toproduce some or all of these features, especially gray scale and/orcolor images and photographs.

In some instances, however, some parts of a multi-layered ID documentstructure, (for example, a structure that includes polyester orpolycarbonate laminate on a core such as TESLIN) can be non-conducive toacceptable engraving of specific types of information. For example, somematerials can be laser engraved (using, for example, a CO₂ laser) withtext information (e.g., dark on light), but cannot be satisfactorilylaser engraved with usable grayscale information (e.g., grayscaleinformation conveying up to 256 shades of gray), such as images orphotographs, or full color information.

Other materials are difficult to laser engrave even with textinformation. For example, some materials, such as silica filledpolyolefin, TESLIN, polycarbonate and fused polycarbonate, polyethylene,polypropylene (PPRO), polystyrene, polyolefin, and copolymers are notvery sensitive to laser radiation and thus are not especially conduciveto laser engraving. Attempts to laser engrave structures that includesuch non-sensitive and non-conducive materials can sometimes result inengraving that appears too faint to be usable to convey informationvisually (although the engraving might be useful to provide a tactilefeel to the structure). Such a multi-layered structure lacks thesensitivity required for favorable laser engraving. The ability toprovide gray scale images on an identification document using a laser,in accordance with the invention, can be advantageous because it canprovide increased security of the identification document. In addition,it may be possible to use the invention incorporate additional securityfeatures (such as digital watermarks) into the laser engraved grayscaleimage.

As noted previously, three components work together to help determinethe speed at which an acceptable laser engraving mark is made with alaser such as a diode pumped YAG laser: materials (card or othersubstrate), image information, laser conditions. What lasermanufacturers have done to aid in this effort (to decrease laser markingtime) has been to increase the power of the laser. In so doing, the heatgenerated per pixel of information is increased, and this heat isdissipated further out. A result of this is an effective decrease in thedots-per-inch (dpi), required of the incoming image data. Reduced dpican help to decrease marking time. Further improvements, as describedherein, have the potential to decrease marking time even further.

In a further aspect of the invention, we have found that, in someinstances, certain properties of the material being laser engraved areimportant factors in the resultant speed of marking of a rastered image.As noted previously, the additives we propose herein can improve thequality of laser engraving, the efficiency of laser engraving, and/orthe speed of laser engraving, in a host material to which they areadded. We have also discovered various ways that the host materialitself (i.e., the material to which the inventive laser enhancingadditive is added) can be altered so that the resulting host materialplus laser enhancing additive responds to the laser energy in a mannerthat can help to reduce the marking time. In particular, we havediscovered various techniques for designing, processing, and/orselecting the host material to be more heat conductive, which can havean effect of decreasing marking time without requiring increased powerfrom the laser machine.

As noted herein elsewhere herein, we have discovered that an additivesystem that includes the inventive laser enhancing additive describedherein (e.g., an additive that comprises, in one embodiment, (a) aneffective amount of least one of copper potassium iodide (CuKI₃), CopperIodide (CuI), potassium iodide (KI), sodium iodide (NaI), and aluminumiodide (AI); and (b) an effective amount of at least one substanceselected from the group consisting of zinc sulfide (ZnS), barium sulfide(BaS), alkyl sulfonate, and thioester) can be very sensitive to laserenergy. However, even with the use of our inventive laser enhancingadditive, there may still be a limitation on dpi of the incoming imageto be around 450-600 dpi. This is due at least in part to the thermalproperties of amorphous polymers, which can cause amorphous polymers toact as insulators rather than conductors.

In one embodiment of the invention, we have found that increasing thethermal conductivity of the host material (which can, for example be apolymer) and its matrices can help to decrease the marking speed ofimages. Thermal conductivity relates to the chemical nature of thematerial and the distance at which heat must travel. Thermal energygenerally prefers to travel along covalent bonds and not weak secondaryones. Thus, by performing actions on the host material that help toincrease the amount of covalent bonds in the host material, it ispossible to further improve the conductivity of the host material (and,of the host material with the inventive laser enhancing additive addedto it).

Although we anticipate that nearly any method to increase thermalconductivity in a material can improve laser marking speed of thatmaterial, we have determined that for at least some advantageousembodiments of the invention, the material being laser engraved not onlyhas its thermal conductivity has been improved using one or more of thetechniques described herein, but also has added to it the inventivelaser enhancing additive described herein. Many methods for increasingthermal conductivity in a material should be usable in accordance withthe invention, and in certain applications it can be beneficial (ordesirable) to increase the thermal conductivity in a manner that permitsthe host material to remain substantially optically clear to laserradiation.

Accordingly, we have found that any one or more of the following methodscan help to improve the thermal conductivity of the host material and/orhost material plus inventive laser enhancing additive system while stillmaintaining an substantially “optically clear to laser energy” polymer:

In one embodiment, we have found that addition of cross linkedfunctionality in the host material, such as by using couplingagents/primers that are reactive and/or form weak secondary bondsbetween the host material and an additive and/or from additive toadditive and/or from host material to additive, can help to improvethermal conductivity in the host material and/or in the host materialplus inventive laser enhancing additive. Usable coupling agents include,for example, those that are used in composite systems to aid inmechanical properties. Such a coupling agent can, for example, form a“bridge” between moieties. For example, we have found for thisembodiment that a good crosslinking agent that can be added to a hostmaterial is gamma-aminopropyltriethoxy silane, which is available fromGeneral Electric (GE) Silicones of Wilton, Conn.

We note, however, that virtually any silicon compounds, silicones,silanes, and/or related products are usable as cross linking/couplingagents/primers, as will be understood by those skilled in the art. Inother embodiments of the invention, we have found that the technicalmanual entitled “Silicon Compounds, Register and Review, Silanes andSilicones for Creative Chemists” (5^(th) ed.), published by HillsAmerica of Piscataway, N.J. (later purchased by United ChemicalTechnologies, inc., whose silicone business was later purchased byCrompton Corporation, whose organosilicone business was later purchasedby GE). We also anticipate that many vinyl additives will be usable withat least some embodiments of the invention.

The amount of additional material required to add sufficientcross-linked functionality so as to improve thermal conductivity can bereadily determined through experimentation, as those skilled in the artwill appreciate. In at least some embodiments of the invention, theadditional material can be added in any concentration that does notreduce optical transparency to laser radiation by an unacceptabledegree. In at least one embodiment, the concentration of this additionalmaterial in the host material by weight is relatively low (e.g., lessthan 10%). In at least one embodiment, the concentration of thisadditional material in the host material, by weight, ranges from 0.001%to 75%.

In another embodiment, we have found that the addition to the hostmaterial of one or more polymers (or other materials) that are morethermally conductive than the host material and that are substantiallyoptically transparent to laser radiation, can help to improve thermalconductivity in the host material and/or in the host material plusinventive laser enhancing additive. In one embodiment, such polymers caninclude one or more polymers such as glass beads, glass fibers, glassthreads, and cross linked moieties, i.e. CR-39, polyurethane. Thoseskilled in the art will recognize that many different thermallyconductive polymers which also are optically substantially transparentto laser radiation are known and could be usable in accordance with theinvention. It also can be possible to use thermally conductive materialsthat are not necessarily substantially transparent to laser radiation aslong as the presence and/or concentrations of the thermally conductivematerials does not interfere with the host material's substantialoptical transparency to laser radiation in a way that is unacceptable.Companies that can supply many different types of thermally conductivepolymers include, for example, Cool Polymers, Inc., of Warwick, R.I.,Epoxies, Etc., of Cranston, R.I., can supply.

The concentrations of “more conductive” polymer/material in the hostmaterial can be (as with cross linking agents) virtually anyconcentration that does not negatively impact the host material'soptical transparency to laser radiation to an unacceptable degree. In atleast one embodiment, the concentration of the “more conductive”polymer/material by weight is relatively low (e.g., less than 10%). Inat least one embodiment, the concentration of this additional materialin the host material, by weight, ranges from 0.001% to 75%.

In at least some embodiments, selection of a particular thermallyconductive polymer will depend at least in part on the particular hostmaterial being used. We anticipate that it may be advantageous to selectthermally conductive polymers that are readily miscible with the hostmaterial. For example, Cool Polymers product number E4503 is a thermally(and electrically) conductive polycarbonate that could be advantageouslyadded to a polycarbonate host material.

In at least one advantageous embodiment, we have found that adding botha cross linking agent (as described above) and a glass product (e.g.,beads, threads, and/or fibers, as described above) can providenoticeable improvements in the thermal conductivity of a host material.

We have also found, in accordance with at least some embodiments of theinvention, that adding materials or performing processes on the hostmaterial to fill up or reduce at least a portion of the free volume inthe host material (while still maintaining the optical transparency ofthe host material to laser radiation at an acceptable level) also can beused to improve the thermal conductivity of the host material. As isunderstood by those skilled in the art, the free volume of a polymercorresponds to the unoccupied regions of the polymer that are accessibleto segmental motions; that is, the excluded volume of a polymer system,i.e. the space not taken up by the polymer atoms. The amount of freevolume can be altered by changing the physical state of the polymer. Forexample, processes such as deformation under compression can reduce freevolume. Processes such as adding a volume filling material to the hostmaterial also can reduce free volume. Volume filling materials can, forexample, include the other techniques and methods described herein thatinvolve adding another material or substance to the host material. Wepresume that those skilled in the art are aware of processes, materials,and techniques for filling up portions, free volume in material, such asa polymer material.

Another technique that we have found for increasing thermal conductivityof a host material, in accordance with one embodiment of the invention,involves processing the host material to change its orientation and/ordensity. We have determined that because the thermal conductivity ofmaterials such as polymers can be at least partially dependent onorientation of the polymer, changing properties of the polymer such asorientation may increase thermal conductivity in a manner that can, inaccordance with at least one embodiment of the invention, improve thespeed and/or efficiency of laser engraving the polymer.

Those skilled in the art will be familiar with the various types ofprocesses and operations that can operate to change orientation and/ordensity of a host material. For example, in one embodiment of theinvention, the host material is processed using a so-called “blowingtunnels” technique. The host material is blown into an elongated tunnel(e.g., a vertical tunnel) and the host material is stretched or orientedin all directions (e.g., cross directions and/or machine directions) togive a strong, substantially stiff material that has a predeterminedorientation or high density. Note that oriented polymers can be stifferalong the chain direction, than unoriented polymers, and can be muchstiffer than those polymers oriented in a transverse direction.Stretching polymer chains, as by the process known as molecularorientation, can cause the polymer chains to orient preferentially in aparticular direction (e.g., monaxial orientation), and this type oforientation can, in at least one embodiment of the invention, increasethermal conductivity of the polymer (or other host material). Thesemethods is not, of course, limiting, and other methods (e.g., spinning,photomanipulation, ribbon extrusion, tubular extrusion, etc.) can, ofcourse, be usable and are intended within the scope of at least someembodiments of the invention. In one embodiment, we anticipate thatprocessing the host material so that it becomes oriented biaxially canbe advantageous for increasing the thermal conductivity of the hostmaterial to improve laser marking speed.

In at least some embodiments, we have found that selecting hostmaterials having relatively high degrees of crystallinity (e.g.,selecting a material such as PET or polyethylene over PC) can help toincrease thermal conductivity and speed of laser engraving. Thoseskilled in the art will appreciate that many other host materials havinghigh degrees of crystallinity (or which have been processed to have highdegrees of crystallinity) can be usable as host materials in theseembodiments provides such materials do not impact the opticaltransparency to laser radiation in an unacceptable manner.

C. FIRST ASPECT OF THE INVENTION C.1 Features

In a first aspect, one embodiment of the invention involves sensitizingat least one of the layers in a multi-layered structure, such as atleast one laminate layer, to help to overcome the problem of thelaminate material not being responsive to laser engraving and/or notbeing responsive enough to be capable of having grayscale images laserengraved thereon. We have found that the quality of laser engraving canbe improved, while reducing engraving time, through over-laminatesensitization using one or more of the inventive formulations describedherein. In one implementation of this embodiment, a layer of laminate ismodified by adding an effective amount of one or more laser sensitiveadditives to the laminate material. We also have found that the lasersensitive additives described herein can be divided over two or morelayers to provide improved laser engraving performance. Moreover (asdescribed later herein in the second and third aspects of theinvention), we have found that the laser sensitive additives also willimprove laser engraving if they are present in a coating applied to amaterial to be engraved.

A least one embodiment of the first aspect of the invention is based onthe surprising discovery that the process of laser engraving ofmaterials such as laminates is improved and enhanced by adding to thelaminate a first effective amount of a first composition, the firstcomposition being at least one of copper potassium iodide (CuKI₃),copper iodide (CuI), Potassium Iodide (KI), Sodium Iodide (NaI), andAluminum Iodide (AlI), and any combination thereof, together with asecond effective amount of a second composition, the second compositionbeing at least one of the following: zinc sulfide (ZnS), barium sulfide(BaS), alkyl sulfonate (e.g., RSO₂Na or R—OSO₂Na), and Thioester (e.g.,substances containing —SH), and any combination thereof. The combinationof the first composition and the second composition will hereinafter bereferred to as the “inventive laser enhancing additive”. The componentsof the inventive laser enhancing additive, namely the componentcomprising at least one of copper potassium iodide (CuKI₃) copper iodide(CuI), Potassium Iodide (KI), Sodium Iodide (NaI), and Aluminum Iodide(AlI), and the component comprising at least one of zinc sulfide (ZnS),barium sulfide (BaS), alkyl sulfonate (e.g., RSO₂Na or R—OSO₂Na), andThioester, will sometimes be referred to as the “inventive laserenhancing additives”).

As those skilled in the art will appreciate, the effective amounts ofthe first and second compositions can vary depending on the material towhich the inventive laser enhancing additive is added and on the laserengraving technique being employed. In at least one embodiment, theinventive laser enhancing additive includes equivalent amounts of thefirst and second compositions. In at least one embodiment, the inventivelaser enhancing additive includes more of the second composition thanthe first composition. In at least one embodiment, the inventive laserenhancing additive includes more of the first composition than thesecond composition.

We have also found an advantageous embodiment of the invention whereinthe laser enhancing additive comprises copper iodide (CuI), PotassiumIodide (KI), Sodium Iodide (NaI), Aluminum Iodide (AlI), together withZinc Sulfide (ZnS).

In addition, we also have found advantageous embodiment of the inventionwherein a first part of the inventive laser enhancing additive has beenchemically analyzed to have the composition shown in Table 1, below, anda second part of the inventive laser enhancing additive has beenchemically analyzed to have the composition shown in Table 2, below.

TABLE 1 Breakdown of one embodiment of first part of the additiveElement % by Weight % by Volume Sodium (Na) 3-7%  9-20% Aluminum (Al)0-5%  0-12% Chlorine (Cl) 0-2%  0-4% Potassium (K) 10-20%  24-38% Copper(Cu) 0.5-5%   0.5-6% Iodine (I) 70-80%  40-50%

TABLE 2 Breakdown of one embodiment of second part of the additiveElement % by Weight % by Volume Zinc (Zn) 60-70% 40-50% Sulfur (S)30-40% 48-58%

Note that although the above tables show relative concentrations ofparticular constituents that make up the additive, these tables do notnecessarily represent their respective concentrations when the inventivelaser enhancing additive is added to the host material. For example (asdiscussed further herein), referring to Table 3 in a given embodimentthe respective concentrations of materials in the additive itself may beas follows:

TABLE 3 Breakdown of one embodiment of the additive Element % by Weight% by Volume Sodium (Na)  5% 25% Aluminum (Al)  3%  5% Chlorine (Cl)  0% 0% Potassium (K) 17% 32% Copper (Cu)  4%  4% Iodine (I) 75% 45% Zinc(Zn) 65% 47% Sulfur (S) 35% 54%

However, the overall percentage of the additive in the host material(e.g., a laminate) in this illustrative embodiment is 0.06%. Therespective breakdown of the percentages of constituent material in thelaminate would thus have to be multiplied by 0.06%, as shown in Table 4below:

TABLE 4 Example of concentrations of constituents in host materialcontaining inventive laser enhancing additive of one embodiment of theadditive % by Weight in Element host material Sodium (Na) 0.5 Aluminum(Al) 0.18 Chlorine (Cl) 0.00 Potassium (K) 1.02 Copper (Cu) 0.24 Iodine(I) 4.50 Zinc (Zn) 3.9 Sulfur (S) 2.16

FIGS. 9-13 show the results of a chemical analysis that we ran on anembodiment of a laser enhancing additive that was eventually added tovarious coatings and laminates. Tables 1 and 2 summarize the results ofthe analysis in FIGS. 9-13. We have found that additives in accordancewith FIGS. 9-13 and Tables 1-3 have worked well for improving theresponsiveness to laser radiation of the material to which they areadded when added to laminates and/or coatings in the concentrations thatare discussed further below. Further details about this improvement andthe concentrations are described herein.

The exact nature of the mechanism by which our various embodiments ofthe inventive laser enhancing additives work is not yet established. Itis possible that the inventive laser enhancing additive increases themolecular activity within the laminate when the heat from the laser isapplied, enabling the laminate to respond faster and/or more intenselyto the laser energy. It also is possible that the additive increases theopacity of the laminate, enabling it to better respond to laser energy.It also is possible that the components of the inventive laser enhancingadditive react with each other and/or with the host material to formblack species within the host material.

Using the inventive laser enhancing additive, high quality images andother engravings can be formed on articles such as multi-layered IDdocuments at acceptable throughput rates by modifying the materialsbeing engraved by adding the inventive laser enhancing additives to thematerial (or by coating the material with a coating containing theinventive laser enhancing additive, as discussed further in the secondaspect of the invention). The inventive laser enhancing additive can notonly make a material that is non-sensitive to laser radiation moresensitive to laser radiation, but also can reduce the laser engravingtime as well. In addition, because the inventive laser enhancingadditive can improve the responsiveness of the material being laserengraved to laser energy, high definition images, such as gray scaleimages (which can be used on identification documents), can be createdwith the laser engraving process. We have also found that in situationswhere a first material containing the laser enhancing additive is ableto co-mingle or otherwise mix with a second material during processing(e.g., during application of heat and/or pressure), the responsivenessto laser energy of the second material is improved.

In at least one embodiment, use of any of the above laser enhancementformulations improves the quality of the laser engraving by increasingthe contrast, (including at least dark colors on light backgrounds) thatcan occur when using a laser having a given power level. In at leastsome embodiments, the increased contrast resulting from use of one ofthe above-described laser enhancing additives may enable the laserengraving to be accomplished using a lower-power laser than would needto be used without user of the laser enhancing additive. It at leastsome embodiments, the increased sensitivity resulting from use of one ofthe above-described laser enhancing additives may reduce the timenecessary to accomplish the laser engraving.

In accordance with at least some embodiments of the first aspect of theinvention, any of the above-described inventive laser enhancingadditives can be added to virtually any material (including all knownthermoplastics and thermosets) to enhance the process of laser markingand/or laser engraving of either the material to which the inventivelaser enhancing additive is added or any material disposed substantiallyadjacent thereto. Advantageously, the addition of the inventive laserenhancing additive enables whatever material(s) it has been added to belaser engraved with a grayscale image.

In accordance with another embodiment of the first aspect of theinvention, a first part of the inventive laser enhancing additive (i.e.,a part that contains an effective amount of at least one of CuI, KI,NaI, an AlI and all combinations thereof) can be added to a first layerof laminate and a second part of the inventive laser enhancing additive(i.e., a second part that contains an effective amount at least one ofZnS, BaS, alkyl sulfonate, and thioester and all combinations thereof)can be added to a second layer of laminate, wherein a single laser beampasses through both layers and enables the laser engraving of either orboth layers. In accordance with still another embodiment of the firstaspect invention, the inventive laser enhancing additive can be added toa core material that is laminated with a material that is transparent tolaser radiation, wherein the core material also can be laser engraved.

In at least one advantageous embodiment, the inventive laser enhancingadditive is added to core, laminate and/or over laminate materials usedin the manufacture of identification documents, to improve the processof laser engraving or marking of the identification documents and toenable laser engraving of a grayscale image on the identificationdocuments.

In another advantageous embodiment, the inventive laser enhancingadditive is added to an image receptive layer (such as the imagereceiving layer described in U.S. Pat. No. 6,066,594), to make the imagereceptive layer a layer that can be imaged both with laser energy andwith another printing method (e.g., D2T2 printing).

Note that the laser enhancing additives in accordance with the inventionare usable for both materials that usually are not sensitive to laserradiation as well as materials that are already sensitive to laserradiation. The inventive laser enhancing additive can be present in amaterial, such as a laminate, at the same time that other compositions(e.g., other laser enhancing or absorbing additives, reinforcingfillers, antioxidants, flame retardants, stabilizers, plasticizers,lubricants, dispersants, and the like) are present in the same materialand/or a separate layer of material. We also note that the presence ofother materials (e.g., contaminants) within the additive, in smallamounts, does not appear to negatively impact the laser enhancingfunction of the inventive laser enhancing additive. For example, in oneembodiment, chemical analysis (see FIGS. 9-13) showed the presence ofadditional constituents in the additive, such as Carbon (C), Oxygen (O),Chlorine (Cl). We further note that it is possible that any or all ofthese additional constituents may, in face, contribute to the laserenhancing properties of this embodiment of the inventive laser enhancingadditive.

Illustrative examples of laminate materials to which the inventive laserenhancing additive may be added include (but are not limited to)polyester, polycarbonate (PC), fused polycarbonate, polyvinyl chloride(PVC), polyethylene, thermosets, thermoplastic and thermoplastic resins(including those that foam when heated), engineering thermoplastics(ETP), polyurethane, polyamides, expanded polypropylene (EPP),polypropylene, acrylonitrile butadiene styrene (ABS), ABS/PC and ABS/PCproducts, high impact polystyrene (HIPS), polyethylene terephthalate(PET), PET-G, PET-F, polybutylene terephthalate (PBS), acetal copolymer(POM), and polyetherimide (PEI), polymer, copolymer, polyester,amorphous polyester, polyolefin, silicon-filled polyolefin, TESLIN,foamed polypropylene film, polystyrene, polyacrylate,poly(4-vinylpyridine, poly(vinyl acetate), polyacrylonitrile, polymericliquid crystal resin, polysulfone, polyether nitride, andpolycaprolactone, as well as virtually any known plastic or polymer. Ofcourse, it will be appreciated that embodiments of the invention haveapplicability for the laser engraving and/or marking of plasticmaterials used to make many different articles formed by virtually anyknown method, including molding and extruding.

In at least some embodiments, the resultant concentration of theinventive laser enhancing additive in the laminate, by weight, rangesfrom 0.001% to 0.1% by weight. Note that in at least some embodiments,the inventive laser enhancing additive is added at larger concentrations(e.g., from 0.1% to 100%). At concentrations larger than 0.1%, theinventive laser enhancing additive can still be used to enhance lasermarking or engraving, but at possible sacrifice of some of thetransparency of the laminating material (if, in fact, the laminatingmaterial is substantially transparent or translucent to begin with).

Advantageously, in at least one embodiment, the laser enhancing additiveis about 0.06% by weight in the laminate. In another advantageousembodiment, the 0.06% by weight includes 0.03% by weight of at least oneof CuI, CuKI₃, KI, NaI, and AlI (and any combinations thereof), and0.03% by weight of at least one of ZnS, BaS, alkyl sulfonate, andthioester (and any combinations thereof). Of course, those skilled inthe art will appreciate that other concentration ranges for the laserenhancing formulations may be usable, especially when using opaquematerials and colored materials. In addition, it will be appreciatedthat the proportions of the at least one of CuI, KI, NaI, AlI, and CuKI₃(and any combinations thereof) and of the at least one of ZnS, BaS,alkyl sulfonate, and thioester (and any combinations thereof) also canvary.

The concentration of the inventive laser enhancing additive that isusable with a given laminate is at least in part dependent on theproperties of the laminate and the ultimate use, durability,environmental conditions, etc., to which the laminate is subject. It ispossible that higher concentrations of the laser enhancing formulationsin the laminate may affect one or more properties of the laminate, suchas transparency, durability, malleability, opacity, rigidity, etc. Ofcourse, appropriate quantities of the additives can be determined for aparticular over-laminate application without undue experimentation.Additional factors may include engraving time and process, baseover-laminate material or composition, and desired engraving quality.

It is contemplated that the inventive laser enhancing additive can beadded to a laminate that is affixed (e.g., by adhesive, lamination,chemical reaction, etc.) to virtually any product, to enable thelaminate to be laser engraved, especially with a grayscale image,thereby producing (especially if the laminate is substantiallytransparent or translucent) a laser engraving or marking on the laminateaffixed to the article. Accordingly, we believe that the inventive laserenhancing laminate has applicability to the manufacture many differentarticles that can be laminated, including but not limited toidentification documents, identification cards, credit cards, prepaidcards, phone cards, smart cards, contact cards, contactless cards,combination contact-contactless cards, proximity cards (e.g., radiofrequency (RFID) cards), electronic components, tags, packaging,containers, building materials, construction materials, plumbingmaterials, automotive, aerospace, and military products, computers,recording media, labels, tools and tooling, medical devices, consumerproducts, and toys. Further, we contemplate that entire articles ofmanufacture could be formed wholly or partially using a material thatcontains the inventive laser enhancing additive and then laser engravedor marked.

C.2 Preparation/Manufacture

The inventive laser enhancing additive can be added to the laminate inmany different ways. The following technique describes the preparationand addition of the inventive laser enhancing additive to the laminatein accordance with one embodiment of the first aspect of the invention.By way of example only, the technique will be described in connectionwith an illustrative embodiment wherein the laminate comprisespolycarbonate and the inventive laser enhancing additive comprises CuI,KI, NaI, and AlI and ZnS, but illustration of this particularformulation should not be viewed as limiting.

In this example, preparation of the inventive laser enhancing additivecan be accomplished by using a twin screw extruder to create a highlyconcentrated polymer blend (so-called “masterbatch”) of the inventivelaser enhancing additive. The masterbatch is created by combining thedesired host material (e.g., polycarbonate) with the inventive laserenhancing additive, (e.g., ZnS and CuI, KI, NaI, and AlI). The hostmaterial and the inventive laser enhancing additive are dried prior toblending to minimize any degradation of each of the components. Thefollowing are illustrative examples of inventive laser enhancingadditive preparations that can be utilized in at least some embodimentsof the invention:

-   -   Masterbatching the inventive laser enhancing additive together        in the same material (e.g., polycarbonate) as the final film        material (e.g., polycarbonate) of the laminate.    -   Masterbatching the inventive laser enhancing additive together        in a different material (e.g., polystryrene) than the final film        material (e.g., polycarbonate) of the laminate.    -   Masterbatching the inventive laser enhancing additive separately        in the same material (e.g., polycarbonate) as the final film        material (e.g., polycarbonate) of the laminate    -   Masterbatching the inventive laser enhancing additive separately        in a different material (e.g., polystyrene) than the final film        material (e.g., polycarbonate) of the laminate.

The above masterbatch formulations are taken and drawn down to thedesired concentration using a single screw extruder to form a monolayerfilm. To reduce costs, a colayer can be made whereby sensitized material(i.e., material to which the inventive laser enhancing additive isadded) is extruded against nonsensitive material. In one embodiment, theoptimum concentration for marking of polycarbonate and maximizingoptical properties is 0.06% by weight. Concentrations can be used up to0.1% by weight; concentrations higher than 0.1% may cause visiblereductions of the transparency of transparent materials. In oneembodiment, more than one of the previously described inventivelaser-enhancing additives can be used as an additive (e.g., ZnS and CuI,KI, NaI, and AlI, along with CuKI₃ along with BaS and CuI), and otherknown laser-enhancing additives can also be combined with one or more ofthe previously described inventive laser-enhancing additives in theabove techniques.

Of course, those skilled in the art will appreciate that the aboveexamples of masterbatch formulations and materials are provided by wayof example and are not limiting. For example, those skilled in the artwill readily understand how the inventive laser enhancing additive canbe adapted to work with acrylics, acetates, polystyrenes, urethanes,polyesters (aromatic and aliphatic), polyether nitrides, ABS andpolyvinyl chloride, as well as the other laminate materials previouslydescribed.

C.3 Illustrative Examples

After the film for the laminate is made, various known processes can beused to adapt it for use with the article being laser engraved ormarked. In the example of an ID document to be laser engraved or marked,the following are illustrative exemplary embodiments for constructing anID document using a film and/or laminate containing the inventive laserenhancing additive.

FIG. 3 is an illustrative cross-sectional view of an ID document 10 inaccordance with a first embodiment of the first aspect of the invention.In this first embodiment, an inventive ID document 10 preferablyincludes a multi-layered structure, as shown in FIG. 3. For purposes ofillustration, however, the ID document 10 may have a front outwardappearance generally similar to the identification document 10 of FIG.1, although the construction and components of the cross-section shownin FIG. 3 differs from the prior art. The identification document 10comprises a layer of core material 50 and at least one layer of a firstlaminate 52 to which the inventive laser enhancing additive has beenadded (a laminate to which the inventive laser enhancing additive isadded will also be referred to herein as the “inventive laminate”). Alaminate layer is preferably added to the front and back surface of thecore to form the multi-layer structure.

In this example, the core material 50 is 10 mils of a substantiallyopaque white laminate core, such as a TESLIN-based core. Prior tolamination, the core material 50 can be pre-printed to include anindicium 54A such as fixed or variable information or data. Thepre-printing can include screen-printing, offset printing, laser orink-jet printing, flexography printing, or the like. “Fixed” informationmay include non-individual dependent information, such as department orcompany information, state information, etc., etc. Variable information,or information that is unique to the ID document holder, can be printed,for example, via a color laser XEROGRAPHY process.

The fixed and/or variable information can also include one or more builtin security features, as well, to help reduce identity fraud. Forexample, in one embodiment of the invention, portions of the ID document10, including either or both of the core material 50 and/or the laminate52, can include a security feature such as a security indicia orsecurity pattern. The security pattern can be applied in an orderedarrangement having a tightly-printed pattern, i.e., having a pluralityof finely-divided printed and unprinted areas in close proximity to oneanother. A tightly-printed pattern may, for example, appear as anoften-repeated logo or design or a fine-line printed security patternsuch is used in the printing of banknote paper, stock certificates andlike and may take the form of filigree, guilloche or other fine-lineprinting. U.S. Pat. No. 4,653,775 provides an example of such securityprinting and is hereby incorporated by reference. Note that the laserengraving facilitated by the invention can be used to print a securityindicia or security pattern.

In addition, the laser engraving facilitated by the invention can beused to add a digital watermark to any indicia printed (whetherconventionally or by laser engraving) on any layer of the ID document10. Digital watermarking is a process for modifying physical orelectronic media to embed a machine-readable code therein. The media maybe modified such that the embedded code is imperceptible or nearlyimperceptible to the user, yet may be detected through an automateddetection process. The code may be embedded, e.g., in a photograph,text, graphic, image, substrate or laminate texture, and/or a backgroundpattern or tint of the photo-identification document. The code can evenbe conveyed through ultraviolet or infrared inks and dyes.

Digital watermarking systems typically have two primary components: anencoder that embeds the digital watermark in a host media signal, and adecoder that detects and reads the embedded digital watermark from asignal suspected of containing a digital watermark. The encoder embeds adigital watermark by altering a host media signal. To illustrate, if thehost media signal includes a photograph, the digital watermark can beembedded in the photograph, and the embedded photograph can be printedon a photo-identification document. The decoding component analyzes asuspect signal to detect whether a digital watermark is present. Inapplications where the digital watermark encodes information (e.g., aunique identifier), the decoding component extracts this informationfrom the detected digital watermark.

Several particular digital watermarking techniques have been developed.The reader is presumed to be familiar with the literature in this field.Particular techniques for embedding and detecting imperceptiblewatermarks in media are detailed, e.g., in Digimarc's co-pending U.S.patent application Ser. No. 09/503,881 and U.S. Pat. No. 6,122,403.Techniques for embedding digital watermarks in identification documentsare even further detailed, e.g., in Digimarc's co-pending U.S. patentapplication Ser. Nos. 10/094,593, filed Mar. 6, 2002, and 10/170,223,filed Jun. 10, 2002, co-pending U.S. Provisional Patent Application No.60/358,321, filed Feb. 19, 2002, and U.S. Pat. No. 5,841,886. Each ofthe above-mentioned U.S. Patent documents is herein incorporated byreference. Additionally, it is noted that the invention encompasses IDdocuments including more or less features than the illustrated IDdocument 10.

Referring again to FIG. 3, after printing, the core material 50 islaminated on both sides with 10 mils of the first laminate 52 that hasbeen sensitized to laser energy by the addition of the inventive laserenhancing additive. In this example, the first laminate 52 contains ZnSand at least one of CuI, KI, NaI, and AlI additives in a base laminatematerial such as polyester or polycarbonate. In one implementation ofthis embodiment, the front and back first laminates 52 can be laminatedusing an adhesive (not visible in FIG. 3) such as co-polyester or olefincontaining adhesive. Other adhesives usable in accordance with thisembodiment of the invention include polyester, polyester urethane,polyether urethane or polyolefin hot melt or ultraviolet or thermallycured adhesive. The multi-layered structure is formed during alamination process, in which adjustments to the processing time,temperature and pressure can be varied to optimize laminations.

In at least some embodiments of the first aspect of the invention,usable laminates usable include those which contain substantiallytransparent polymers and/or substantially transparent adhesives, orwhich have substantially transparent polymers and/or substantiallytransparent adhesives as a part of their structure, e.g., as an extrudedfeature. The first laminate 52 can comprise a plurality of separatelaminate layers, for example a boundary layer and/or a film layer. Thefirst laminate 52 can comprise an optically clear durable plastic film,such as amorphous or biaxially oriented polyester. In at least someembodiments, the laminate need not be substantially transparent, but canbe colored or opaque, so long as a grayscale image can be laser engravedonto it. Of course, the types and structures of the laminates describedherein are provided only by way of example, those skilled in the artwill appreciated that many different types of laminates are usable inaccordance with the invention.

In at least some embodiments, the first laminate layers 52 can provideadditional security features for the identification document 10. Forexample, the first laminate 52 may include a low cohesivity polymericlayer, an optically variable ink, an image printed in an ink which isreadable in the infra-red or ultraviolet but is invisible in normalwhite light, an image printed in a fluorescent or phosphorescent ink, orany other available security feature which protects the document againsttampering or counterfeiting, and which does not compromise the abilityof the first laminate 52 to be laser engraved.

In at least one embodiment (not shown), the first laminate is formedinto a pouch into which the core material 50 slips. With a pouch,methods such as heat, pressure, adhesives, and the like, are usable tobond the core material 50 to the first laminate 52 formed into a pouch.Those skilled in the art will appreciate that many known structures andconfigurations for laminating are usable with the invention.

Referring again to FIG. 3, adhesive can be applied to the first laminate52 via methods such as solvent coating, casting, or hot melt extrusion.The adhesive may also be coated, cast or extruded onto a surface of thecore material 50. The first laminate 52 can then be heat laminated tothe core material 50 to form a secure bond. Additional processes thatcan be used to form the first laminate 52 onto the core material includeinjection molding or extrusion of a hot melt onto the core material 50.Those skilled in the art will appreciate that virtually any known methodcan be used to couple the first laminate 52 to the core material 50. Forexample, techniques such as standard heat and pressure, pressure only,chemical fusion via solvent blending, ultraviolet (UV) methodologies,and/or electron beam (EB) methodologies can be used to laminate thefirst laminate 52 to the core material 50.

When first laminate 52 is appropriately coupled to the core material 50,the ID document 10 is ready for laser engraving. In at least oneembodiment, the laser engraving is used to personalize the ID document.In at least one embodiment, a usable laser for engraving is aneodymium:yttrium aluminum garnet (Nd:YAG) laser using both 3 Watt (W)(103 D) and 10 W (Powerline E) power outputs (a laser that is usablewith at least one embodiment of the invention can be purchased fromRofin Baasel Lasertech of Boxborough, Mass.). The 10 W laser of thisdevice uses a true grey scale marking software compared to the 3 W whichdoes not. In at least one embodiment, the Nd:YAG laser emits light at awavelength of about 1064 nanometers (nm).

Because the inventive laser enhancing additive improves theresponsiveness of the first laminate 52 to the laser, the time to laserengrave a given area can be decreased as compare to the time to mark agiven area in a laminate that does not have the inventive laserenhancing additive, when using the same laser”. In addition, theimprovement in responsiveness can enable grayscale images, such asimages with up to 256 different shades of gray, to be laser engravedinto the laminate 52, especially when an Nd:Yag laser (including lamppumped YAG lasers, diode pumped Nd:Yag lasers, and light pumped Nd:Yaglasers) is used. Those skilled in the art will appreciate that theeffective amount of the inventive laser enhancing additive used and thematerial in which it is used can be adapted to achieve similarimprovements in laser engraving when using other types of lasers, suchas, excimer lasers and CO₂ lasers.

In addition, use of the inventive laser enhancing additive can improvethe laser engraving of so-called “vector information” of anidentification document. Vector information is non-captured information(such as logos) in an identification document and generally does notinclude so-called “pixel” information, which is information that iscaptured, such as signature images and/or photographic images. When theinventive laser enhancing additive is added to a material being laserengraved with vector information, it is possible to sufficientlysensitize the material such that the vector information can be engravedto achieve the “tactile feel” known in the art of laser engraving.

Referring again to FIG. 3, one or more indicia 54B-54F, such as variableinformation (e.g., birth date, address, biometric information, etc.) isengraved into the over laminate layer 52 through a focused laser beam.In one embodiment, the laser used is an Nd:YAG laser; other suitablelasers (e.g., CO₂) can, of course, be similarly employed. As describedpreviously, the area irradiated by the laser absorbs the laser energyand produces heat which causes a visible discoloration in the firstlaminate 52. The visible discoloration serves as a “mark” or indicator.With some laminates and lasers, the heat from the laser beam causes afoaming as shown in indicia 54D; the foaming can create a raised area inthe first laminate 52 that provides a tactile feel when touched. Theindicia 54B-F can comprise virtually any type of information, includingphotographs, data, images, fingerprints, and text. Although not apparentin the cross sectional view of FIG. 3, our testing has shown that theindicia 54B-F can comprise a usable grayscale image (by usable, it is atleast meant that image can be used for security purposes, such asidentification or authentication). In experiments, the inventor was ableto engrave an acceptable gray scale photograph, non-tactile text andtactile text into the laminate layer 52. We further note that thetechnology described in a commonly assigned patent application entitled“Enhanced Shadow Reduction System and Related Technologies for DigitalImage Capture” (Application No. not yet assigned, Attorney Docket No.P0883D, filed Sep. 15, 2003—Inventors Scott D. Haigh, Tuan A. Hoang,Charles R. Duggan, David Bohaker, and Leo M. Kenen), and its predecessorprovisional patent applications, can be used to further improve imagesprinted with a laser in accordance with one embodiment of the invention(by reducing shadows and improving image quality). As an example, wecompared laminate to which the inventive laser enhancing additive wasadded (in this test, we used formulations of an additive based on thoseshown in FIGS. 9-13), the additive comprising ZnS and CI plus KI plusNaI plus AlI) against a commercially available polycarbonate laminate,manufactured by the Bayer Polymer Division. We engraved a 0.75-inch by1.0-inch photograph at 750 dpi in each of the Bayer material and ourinventive over-laminate containing the inventive laser enhancingadditive. Using the same laser at the same power for each (a 3 W 103 Dlaser, as described above), we found that the Bayer material requiredapproximately 40 seconds to engrave an acceptable gray scale photograph.In comparison, the laminate to which the inventive laser enhancingadditive was added needed only approximately 20 seconds to engrave anacceptable gray scale photograph by adjusting the frequency of thelaser.

Although the embodiment of FIG. 3 illustrates that the first laminate 52that contains the inventive laser enhancing additive overlayssubstantially all of the core material 50, in at least some embodimentsof the invention, the inventive laser enhancing additive can be added toa laminate that forms merely a portion of the laminate covering a corematerial 50.

For example, FIG. 4 is an illustrative cross sectional view of anidentification document in accordance with a second embodiment of thefirst aspect of the invention. In the embodiment of FIG. 4, the IDdocument 10 preferably includes a multi-layered structure. For purposesof illustration, however, the ID document 10 may have a front outwardappearance generally similar to the identification document 10 of FIG.1, although the construction and components of the cross-section shownin FIG. 4 differs from the prior art. In the embodiment of FIG. 4, theportion of first laminate 52 containing the inventive laser enhancingadditive is disposed at least partially within a layer of anothermaterial, such as so-called “plain” laminate 56 (i.e., laminate thatdoes not contain the inventive laser enhancing additive). When a laserbeam is applied to the first laminate 52, a third indicium 54G isformed. The plain laminate 56 may comprise a material that is inherentlysensitive to laser radiation or can be a material that is insensitive tolaser radiation. Note also that the layer of other material in which thefirst laminate 52 containing the inventive laser enhancing additive isdisposed need not even be a laminate at all. Thus, in some articles, thesurface of the article can include a portion or “window” of firstlaminate 52 containing the inventive laser enhancing additive, whereasthe rest of the surface is some other material (e.g., ceramic). Thisconfiguration may be applicable, for example, in the marking ofelectronic components and/or devices.

FIG. 5 is an illustrative cross sectional view of an identificationdocument 10 in accordance with a third embodiment of the first aspectinvention. In the embodiment of FIG. 5, the ID document 10 preferablyincludes a multi-layered structure. For purposes of illustration,however, the ID document 10 may have a front outward appearancegenerally similar to the identification document 10 of FIG. 1, althoughthe construction and components of the cross-section shown in FIG. 5differs from the prior art. In the embodiment of FIG. 5, a first portionof the inventive laser enhancing additive is disposed in a firstlaminate layer 52 and a second portion of the inventive laser enhancingadditive is disposed in a second laminate layer 55. Specifically, inthis embodiment, the first laminate layer 52 contains an effectiveamount of at least one of copper potassium iodide (CuKI₃), copper iodide(CuI), Potassium Iodide (KI), Sodium Iodide (NaI), and Aluminum Iodide(AlI) and the second laminate layer 55 contains an effective amount ofat least one of the following: zinc sulfide (ZnS), barium sulfide (BaS),alkyl sulfonate and thioester. The first laminate layer 52 and secondlaminate layer 55 are constructed and arranged so that a laser beam canpass through both the first laminate layer 52 and the second laminatelayer 55, to form indicia 66, 64 in one or both of the first and secondlaminate layers 52, 55, respectively. As those skilled in the art willappreciate, whether an indicia is formed in a given laminate layerdepends on the particular type of laser used the manner in which thelaser is used (e.g., pumped), and the duration of the application oflaser energy.

It should be understood that although the example of FIG. 5 shows thatthe first laminate layer 52 contains the effective amount of at leastone of copper potassium iodide (CuKI₃), copper iodide (CuI),), PotassiumIodide (KI), Sodium Iodide (NaI), and Aluminum Iodide (AlI) and thesecond laminate layer 55 contains the effective amount of at least oneof zinc sulfide (ZnS), barium sulfide (BaS), alkyl sulfonate andthioester, the positions of the two compounds in the respective firstand second layers could be reversed. That is, the first laminate layer52 could contain the effective amount of at least one of zinc sulfide(ZnS), barium sulfide (BaS), alkyl sulfonate and thioester, and thesecond laminate layer 55 could contain the effective amount of copperpotassium iodide (CuKI₃), copper iodide (CuI),), Potassium Iodide (KI),Sodium Iodide (NaI), and Aluminum Iodide (AlI).

Referring again to FIG. 5, the ID document 10 further comprises a layerof core material 50 (in this example, the layer of core material is10-20 mils thick) to which the first laminate 52 is laminated on eitherside. The core material 50 is printed with pre-printing 70 on its outersurface. In one embodiment, the pre-printing 70 is nonvariableinformation, such as organization name, logo, and the like. The firstlaminate layer 52 can also be printed with printed information 72 usinga technique such as dye diffusion thermal transfer. Also, in FIG. 5, athird layer 57 is disposed between the first laminate layer 52 and thesecond laminate layer 55. The third layer 57 is a material (for example,a laminate or an adhesive) that is transparent to laser radiation andpermits a laser beam directed at the second layer 55 to penetrate, atleast partially to the first layer 52.

In at least one embodiment, the first laminate 52 can be made from amaterial that is inherently (i.e., even without the addition of theinventive laser enhancing additive or any portion thereof) moreresponsive to laser radiation than is the second laminate 55. In thisembodiment, when a laser beam is directed through the second and firstlaminate layers 55, 52, the area in the first laminate 52 that isirradiated can “bubble up” to the second layer 55, to form a bond 68between the first laminate 52, second laminate 55, and (optionally) thethird layer.

In one embodiment, the ID document 10 of the embodiment of FIG. 5 is amulti-layer fused polycarbonate structure used as an ID document. Themulti-layered structure preferably includes a core and at least a topand bottom over-laminate. The core material 50 may include a titaniumdioxide (TiO₂) filled polycarbonate (PC) film, which generally has awhitish color. The core material 50 can have pre printed information 70thereon prior to the fusing process. Examples of acceptable pre-printingprocesses include screen-printing, offset printing, laser or ink-jetprinting, flexography printing, and the like.

The core material 50 and first laminate 52 are fused (e.g., using heatand pressure, such as by a platen press) together to form a structure53, which helps to deter delaminating attempts. The structure 53 in thisexample is a solid PC ID document 10. Adjusting the time, temperatureand pressure can help to bond the first laminate 52 to the polycarbonatecore material 50. The second laminate 55 can be an overlaminatematerial.

In one experiment, we compared the engraving properties of an inventivefused polycarbonate structure, including a titanium dioxide filledpolycarbonate core and polycarbonate over-laminates with ZnS and(CuI+KI+NaI+AlI) additives, against a Muhlbauer polycarbonate card. Thecomparison involved engraving a 0.75 by 1.0 inch photograph at 750 dpi.The Muhlbauer engraving required between 20 and 25 seconds, while theinventive fused polycarbonate structure required 11-15 seconds engravingtime to achieve similar acceptable gray scale tones by adjusting thefrequency of the laser.

The inventive laser enhancing additive also can be used in a laminatethat has one or more additional laminate layers bonded over it. Forexample, FIG. 6 is an illustrative cross sectional view of anidentification document in accordance with a fourth embodiment of theinvention. In the embodiment of FIG. 6, the ID document 10 preferablyincludes a multi-layered structure. For purposes of illustration,however, the ID document 10 may have a front outward appearancegenerally similar to the identification document 10 of FIG. 1, althoughthe construction and components of the cross-section shown in FIG. 6differs from the prior art. In FIG. 6, the ID card 10 includes a corematerial 50 (shown for illustrative purposes only to be about 10 milsthick) to which is laminated a layer (shown for illustrative purposesonly to be about 5 mils thick) of first laminate 52 to which theinventive laser enhancing additive is added. Over the first laminate 52is a layer of second laminate 58 (shown for illustrative purposes to beabout 5 mils thick), which in this embodiment is made from a materialthat is not sensitive to laser radiation. In this example, the secondlaminate 58 is a transparent material. A laser is used to engrave thefirst laminate 52 with indicia 54I-54J. The total thickness of the IDdocument 10 of FIG. 6 is about 30 mils, which, in at least oneembodiment, allows the architecture of the ID document 10 to meet and/orexceed American Association of Motor Vehicle Administrators (AAMVA),American National Standards Institute (ANSI). The total thickness of theID document 10 of FIG. 6 can also be adapted to meet and InternationalOrganization for Standardization (ISO) specifications for identificationdocuments such as ID Cards. It will be appreciated that many otherthicknesses of layers are usable to make an ID document that satisfiesone or more of the AAMVA, ANSI, and ISO requirements. For example, inFIG. 6, the core material 50 could be 20 mils thick, the first laminate52 could be 2 mils thick, and the second laminate 58 could be 3 milsthick.

Although FIG. 6 only illustrates a single layer of laminate over thefirst laminate 52 (which has added to it the inventive laser enhancingadditive), it will be appreciated that many more layers can be addedover the first laminate 52, so long as the laser being used is able toreach the first laminate 52.

We have found that the inventive laminates described herein may offerone or more advantages. For example, using the inventive laminates canenable the inventive laminates to be laser marked or engraved withusable grayscale images. In addition, using the inventive laminates canenable faster laser engraving or marking at lower laser power levels.Further, the laser engraving that is possible using the inventivelaminates is durable, abrasion resistant, and environmentally friendly.

C.4 Additional Embodiments of First Aspect of the Invention

We anticipate that at least the following combinations, and others likethem, can be useful embodiments of the first aspect of the invention:

1. A composition having laser engraving properties, comprising:

a host material; and

an effective amount of a laser enhancing additive, the laser enhancingadditive comprising:

-   -   a first quantity of at least one of copper potassium iodide        (CuKI₃), Copper Iodide (CuI), Potassium Iodide (Kr), Sodium        Iodide (NaI), and Aluminum Iodide (AlI); and    -   a second quantity of at least one substance selected from the        group consisting of zinc sulfide (ZnS), barium sulfide (BaS),        alkyl sulfonate, and thioester.

2. The composition as recited in 1 above, wherein the laser enhancingadditive is present in an amount from about 0.001 to 100 percent byweight based on the total weight of the composition.

3. The composition as recited in 1 above wherein host material issubstantially transparent and the laser enhancing additive is present inan amount from about 0.001 to 0.1 percent by weight based on the totalweight of the composition.

4. The composition as recited in 1 above wherein the laser enhancingadditive is present in an amount that is about 0.06 percent by weightbased on the total weight of the composition.

5. The composition as recited in 4 above, wherein the first and secondquantities each comprise about 0.03 percent by weight based on the totalweight of the composition.

6. The composition as recited in 1 above wherein the first quantity andthe second quantity are the same.

7. The composition as recited in 1 above wherein the first quantity isgreater than the second quantity.

8. The composition as recited in 1 above wherein the first quantity isless than the second quantity.

9. The composition as recited in 1 above wherein the composition islaser engraveable by at least one of a diode pumped Nd:Yag laser, lightpumped Nd:Yag laser, CO₂ laser and excimer laser.

10. The composition as recited in 8 above wherein the composition islaser engraveable to form a grayscale image.

11. The composition as recited in 1 above wherein the host materialcomprises a material that is not, by itself, sufficiently sensitive tolaser radiation to permit gray scale images to be laser engraved in thehost material.

12. The composition as recited in 1 above wherein the host materialcomprises at least one material selected from the group consisting ofthermosetting material, thermoplastic, polymer, copolymer,polycarbonate, fused polycarbonate, polyester, amorphous polyester,polyolefin, silicon-filled polyolefin, TESLIN, foamed polypropylenefilm, polyvinyl chloride, polyethylene, thermoplastic resins,engineering thermoplastic, polyurethane, polyamide, polystyrene,expanded polypropylene, polypropylene, acrylonitrile butadiene styrene(ABS), ABS/PC, high impact polystyrene, polyethylene terephthalate(PET), PET-G, PET-F, polybutylene terephthalate PBT), acetal copolymer(POM), polyetherimide (PEI), polyacrylate, poly(4-vinylpyridine,poly(vinyl acetate), polyacrylonitrile, polymeric liquid crystal resin,polysulfone, polyether nitride, and polycaprolactone.

13. An article of manufacture capable of being laser engraved with agrayscale image, comprising:

a core layer having a first surface;

a first layer comprising a first host material, the first host materialcomprising an effective amount of a first laser enhancing additivecomprising at least one of one of copper potassium iodide (CuKI₃),Copper Iodide (CuI), Potassium Iodide (KI), Sodium Iodide (NaI), andAluminum Iodide (AlI); and

a second layer comprising a second host material, the second layeroriented in relation to the first host material such that a single laserbeam can penetrate both at least a portion of the first layer and atleast a portion of the second layer, the second host material comprisingan effective amount of a second laser enhancing additive, the secondlaser enhancing additive selected from the group consisting of zincsulfide (ZnS), barium sulfide (BaS), alkyl sulfonate, and thioester;

wherein the first and second layers are operably coupled to each otherand at least one of the first and second layers is operably coupled tothe first surface of the core layer.

14. The article of manufacture as recited in 13 above, furthercomprising a grayscale image laser engraved into at least one of thefirst and second layers.

15. The article of manufacture recited in 13 above, wherein the articleof manufacture is an identification document.

16. The article of manufacture of recited in 13 above, wherein the firstlayer is substantially transparent and the first laser enhancingadditive is present in an amount from about 0.001 to 0.100 percent byweight based on the total weight of the first host material.

17. The article of manufacture recited in 13 above, wherein the secondlayer is substantially transparent and the second laser enhancingadditive is present in an amount from about 0.001 to 1.00 percent byweight based on the total weight of the second host material.

18. The article of manufacture recited in 13 above wherein at least oneof the first and second host materials comprises a material that is lesssensitive to laser radiation than the other of the first and second hostmaterials.

19. The article of manufacture recited in 13 above, wherein at least oneof the first and second host materials comprises at least one materialselected from the group consisting of thermosetting material,thermoplastic, polymer, copolymer, polycarbonate, fused polycarbonate,polyester, amorphous polyester, polyolefin, silicon-filled polyolefin,foamed polypropylene film, polyvinyl chloride, polyethylene,thermoplastic resins, engineering thermoplastic, polyurethane,polyamide, polystyrene, expanded polypropylene, polypropylene,acrylonitrile butadiene styrene (ABS), ABS/PC, high impact polystyrene,polyethylene terephthalate (PET), PET-G, PET-F, polybutyleneterephthalate PBT), acetal copolymer (POM), polyetherimide (PEI),polyacrylate, poly(4-vinylpyridine, poly(vinyl acetate),polyacrylonitrile, polymeric liquid crystal resin, polysulfone,polyether nitride, and polycaprolactone.

20. The article of manufacture recited in 13 above further comprising athird layer disposed between the first and second layers, the thirdlayer comprising a material that permits transmission of a laser beamtherethrough.

21. The article of manufacture recited in 13 above, wherein the firstand second layers are substantially transparent.

22. The article of manufacture recited in 13 above, wherein the corelayer is substantially opaque.

23. A method of engraving a material by exposing the material to laserradiation, comprising:

adding to the material an effective amount of a laser enhancingadditive, the laser enhancing additive comprising:

-   -   at least one of copper potassium iodide (CuKI₃), Copper Iodide        (CuI), Potassium Iodide (KI), Sodium Iodide (NaI), and Aluminum        Iodide (AlI); and    -   at least one substance selected from the group consisting of        zinc sulfide (ZnS), barium sulfide (BaS), alkyl sulfonate, and        thioester; and

exposing the material to laser radiation in a manner that causes thematerial to be engraved by the laser radiation.

24. The method recited in 23 above wherein the effective amount of thelaser enhancing additive comprises 0.001% to 100% by weight of thematerial.

25. The method recited in 23 above wherein the material is substantiallytransparent and wherein the effective amount of the laser enhancingadditive comprises 0.001% to 0.1% by weight of the material.

26. The method recited in 23 above further comprising laser engraving anindicium in grayscale in at least a portion of the material.

27. The method recited in 23 above further comprising using the laserengraved material in the manufacture of an identification document.

28. A method of laser engraving a gray scale image on an article havingfirst and second layers, comprising:

adding to the first layer a first effective amount of least one ofcopper potassium iodide (CuKI₃), Copper Iodide (CuI), Potassium Iodide(KI), Sodium Iodide (NaI), and Aluminum Iodide (AlI);

adding to the second layer a second effective amount of at least onesubstance selected from the group consisting of zinc sulfide (ZnS),barium sulfide (BaS), alkyl sulfonate, and thioester; and

directing a laser beam so that it passes through at least a portion ofthe first layer and at least a portion of the second layer to form agrayscale image in at least one of the first and second layers.

29. The method recited in 23 above, further comprising:

directing a laser beam so that it that it passes through at least aportion of the first layer and at least a portion of the second layersuch that the first and second layers become affixed to each other.

30. The method recited in 28 above wherein the first effective amountand the second effective amount together comprise about 0.001 to 0.1percent by weight of the total weight of the first and second layers.

31. The method recited in 28 above further comprising using the materialin the manufacture of an identification document.

32. A multilayer identification document, comprising:

a core layer;

a film layer overlaying at least a portion of the core layer and affixedto the portion of the core layer, the film layer comprising an additivethat comprises:

-   -   an effective amount of least one of copper potassium iodide        (CuKI₃), Copper Iodide (CuI), Potassium Iodide (KI), Sodium        Iodide (NaI), and Aluminum Iodide (AlI); and    -   an effective amount of at least one substance selected from the        group consisting of zinc sulfide (ZnS), barium sulfide (BaS),        alkyl sulfonate, and thioester.

33. The identification document recited in 32 above, wherein theidentification document bears a first indicium thereon, the indiciaobtained by exposing the film layer to a laser beam.

34. The identification document recited in 33 above, wherein the indiciacomprises at least one of a gray scale image, photograph, text, tactiletext, graphics, information, security pattern, security indicia, anddigital watermark.

35. The identification document recited in 33 above wherein the firstindicium comprises variable information.

36. The identification document recited in 32 above, wherein the filmlayer is substantially transparent and wherein the additive comprisesabout 0.001 to 0.10 percent by weight of the film layer.

37. The identification document recited in 36 above, wherein the filmlayer further comprises:

a first sub layer comprising an effective amount of least one of copperpotassium iodide (CuKI₃), Copper Iodide (CuI), Potassium Iodide (IU),Sodium Iodide (NaI), and Aluminum Iodide (AlI); and

a second sub layer comprising an effective amount of at least onesubstance selected from the group consisting of zinc sulfide (ZnS),barium sulfide (BaS), alkyl sulfonate, and thioester.

38. A process for making an identification document, comprising:

overlaying at least a portion of a core layer with a film layer, thefilm layer comprising:

-   -   at least one of copper potassium iodide (CuKI₃), Copper Iodide        (CuI), Potassium Iodide (KI), Sodium Iodide (NaI), and Aluminum        Iodide (AlI); and    -   at least one substance selected from the group consisting of        zinc sulfide (ZnS), barium sulfide (BaS), alkyl sulfonate, and        thioester; and affixing the film layer to the portion of the        core layer.

39. The process recited in 38 above, further comprising directing alaser beam to at least a portion of the film layer to produce a firstgrayscale indicium in the portion of the film layer.

D. SECOND ASPECT OF THE INVENTION D.1 Features

In a second aspect of the invention, the above-described inventive laserenhancing additive can be added to a coating on a at least a portion ofa surface to be laser engraved or marked, to help to overcome theproblem that the material being laser engraved or marked is responsiveto laser engraving and/or is not responsive enough to be capable ofhaving grayscale images laser engraved thereon. We have found that theability to laser engrave at least some materials can be improved and/orthe time to laser engrave at least some materials can be reduced, bycoating the area of the given material to be engraved with a coatingthat contains the inventive laser enhancing additive. Note also that thecoating containing the inventive laser enhancing additive can be appliedto a laminate or another coating. We also have found that the compoundsthat make up the inventive laser sensitive additives described hereincan be divided over two or more coatings, or a coating and a laminate,to provide improved laser engraving performance.

A least one embodiment of the second aspect of the invention is based onthe surprising discovery that the process of laser engraving ofmaterials, especially materials used in the manufacture ofidentification documents, is improved and enhanced by coating the areaof the material to be engraved with a coating that includes a firsteffective amount of a first composition, the first composition being atleast one of copper potassium iodide (CuKI₃), copper iodide (CuI),Potassium Iodide (KI), Sodium Iodide (NaI), and Aluminum Iodide (AlI)(and any combination thereof) together with a second effective amount ofa second composition, the second composition being at least one of thefollowing: zinc sulfide (ZnS), barium sulfide (BaS), alkyl sulfonate(e.g., RSO₂Na or R—OSO₂Na), and Thioester (e.g., substances containing—SH) (and any combination thereof). As with the first aspect of theinvention, the combination of at least one of CuI, KI, NaI, AlI (and anycombination thereof), and CuKI₃ together with at least one of ZnS, BaS,alkyl sulfonate, and thioester (and any combination thereof) continuesto be referred to as the “inventive laser enhancing additive”.

In at least some embodiments, the resultant concentration of theinventive laser enhancing additive in the coating, by weight, rangesfrom 0.001% to 0.1% by weight. In at least some embodiments, theinventive laser enhancing additive is added at larger concentrations(e.g., from 0.1% to 100%). At concentrations larger than 0.1%, theinventive laser enhancing additive can still be used to enhance lasermarking or engraving of an article or surface being coated, but atpossible sacrifice of some of the transparency of the coating (if, infact, the coating is substantially transparent or translucent to beginwith). Advantageously, in at least one embodiment, the laser enhancingadditive is about 0.06% by weight in the coating. In anotheradvantageous embodiment, the 0.06% by weight includes 0.03% by weight ofat least one of CuI, KI, NaI, AlI, and CuKI₃ (and any combinationthereof) and 0.03% by weight of at least one of ZnS, BaS, alkylsulfonate, and thioester (and any combination thereof).

We further note that the previous examples and concentrations discussedin connection with FIGS. 9-13 and Tables 1-4 are equally applicable tocoatings as they are to laminates.

Of course, those skilled in the art will appreciate that otherconcentration ranges for the laser enhancing formulations may be usable,especially when the coating is applied to opaque materials and coloredmaterials. In addition, it will be appreciated that the proportions ofthe at least one of CuI, KI, NaI, AlI, and CuKI₃ can vary, as canproportions of the at least one of ZnS, BaS, alkyl sulfonate, andthioester also can vary. That is, a given composition could have, forexample (using for purely illustrative purposes the example of acomposition containing CuI and BaS), equal amounts of CuI and BaS, or 3parts CuI to 5 parts BaS, 2 parts CuI to 1 part BaS, etc. We expect thatthose skilled in the art will be able to determine optimum proportionswithout undue experimentation. In addition, we note that at least oneadvantageous compound that we have tested uses the two sub compositions(e.g., the CuI and BaS, in this example) in equal proportions.

The concentration of the inventive laser enhancing additive that isusable with a given coating is at least in part dependent on theproperties of the coating (especially the binder material in thecoating) laminate and the ultimate use, durability, environmentalconditions, etc., to which the coating is subject. It is possible thathigher concentrations of the laser enhancing formulations in the coatingmay affect one or more properties of the coating, such as transparency,durability, malleability, opacity, rigidity, etc. Of course, appropriatequantities of the additives can be determined for a particular coatingapplication without undue experimentation. Additional factors mayinclude engraving time and process and desired engraving quality.

It is contemplated that the inventive laser enhancing additive can beadded to a coating that is applied (by virtually any known method) tovirtually any surface, article, or product, to enable the surface,article, or product to be laser engraved, especially with a high qualitygrayscale image. Accordingly, we believe that the inventive laserenhancing laminate has applicability to the manufacture many differentarticles that can be coated, including but not limited to identificationdocuments, identification cards, credit cards, prepaid cards, phonecards, smart cards, contact cards, contactless cards, combinationcontact-contactless cards, proximity cards (e.g., radio frequency (RFID)cards), electronic components, tags, packaging, containers, buildingmaterials, construction materials, plumbing materials, automotive,aerospace, and military products, computers, recording media, labels,tools and tooling, medical devices, consumer products, and toys.Further, we contemplate that entire articles of manufacture could beformed wholly or partially using a coating material that contains theinventive laser enhancing additive and then laser engraved or marked.

As those skilled in the art will appreciate, the effective amounts ofthe first and second compositions that are added to the coating can varydepending on the type of coating (e.g., the binder material and/or otheradditives present in the coating), the material being coated, and on thelaser engraving technique being employed. In at least one embodiment,the inventive laser enhancing additive in the coating includesequivalent amounts of the first and second compositions described above.In at least one embodiment, the coating includes more of the secondcomposition than the first composition. In at least one embodiment, thecoating includes more of the first composition than the secondcomposition.

As those skilled in the art also will appreciate, the inventive laserenhancing additive can be added to many different types of coatings,including organic coatings and aqueous coatings, substantiallytransparent coatings and non-transparent coatings. In addition, in atleast some embodiments, the coating containing the inventive laserenhancing additive can further comprise a binder, which can be, forexample, latex, emulsion, a thermoset binder or a thermoplastic binder.Illustrative examples of binder materials which we have found to beusable include resins, polyesters, polycarbonates, vinyls, acrylates,urethanes, and cellulose based materials. We anticipate that thoseskilled in the art will readily be able to formulate coatings containingthe inventive laser enhancing additive using many other bindermaterials, such as lacquer, varnish, latex, acrylic, epoxy resins,nitrocellulose, alkyd resins, melamine formaldehyde, polyamides,silicone, and polyvinyl butyral. Those skilled in the art also willappreciate that virtually any resin able to be formed into a coatingcould be used with the invention. Of course, a coating containing theinventive laser enhancing additive can also include other additivesknown in the art, such as colorants (e.g., pigments or dyes),stabilizers, lubricants, adhesion promoting agents, toners, surfactants,anti-static agents, thickeners, thixotropic agents, and the like.

By applying a coating containing the inventive laser enhancing additive(also referred to herein as the “inventive coating”) to a surface of amaterial to be laser engraved, we have found that we can form highquality images and other engravings on articles such as multi-layered IDdocuments, at acceptable throughput rates. The high quality images caninclude both grayscale laser engraved images (as described herein) andfull color laser engraved images (which are more particularly describedin applicants' commonly assigned U.S. patent application, applicationSer. No. 10/330,034, entitled “Systems, Compositions, and Methods forFull Color Laser Engraving of ID Documents,” attorney docket no. P0734D,filed Dec. 24, 2002). Further, we anticipate that the inventive coatingcan be applied to virtually any part of the surface of any article wherelaser marking, especially laser engraving of grayscale images, isdesired. The entire article or surface need not be coated.

We believe that the laser engraving or marking of various articles,including but not limited to identification documents, identificationcards, credit cards, prepaid cards, phone cards, smart cards, contactcards, contactless cards, combination contact-contactless cards,proximity cards (e.g., radio frequency (RFID) cards), electroniccomponents, tags, packaging, containers, building materials,construction materials, plumbing materials, automotive, aerospace, andmilitary products, computers, recording media, labels, tools andtooling, medical devices, consumer products, toys, etc., can be improvedby coating the surface of the article to be engraved with the inventivecoating. This improvement can be achieved on articles whose surface is alaminate to be laser engraved. In addition, the inventive coating, ascontemplated herein, can be applied over other coatings (or materials)that cover the surface of an article to be laser engraved or marked, solong as the “intervening” materials between the surface being laserengraved or marked and the inventive coating are transparent to laserradiation.

In at least one embodiment, the inventive coating is used to improve themanufacture of an identification document, such as the identificationdocument 10 shown in FIGS. 1 and 2. The security of the document can beenhanced through selective coating of the core layer of theidentification document 10 with the inventive coating Because thecoating material can be applied through a controlled process (e.g.,offset, flexography, pad printing, or screen printing), the placement ofthe inventive coating (and, thus, the laser enhancing additive) can beprecisely controlled. The coating material is sensitive (or responsiveto) the laser, so the placement of the inventive coating dictates thelocation of the engraved information. Selective placement of the lasersensitive materials also helps to prevent counterfeiting, since thelaser engraveable areas are limited.

In one embodiment, the inventive coating is applied to an identificationdocument and the issuing authority for the identification document(e.g., a state's DMV, a passport authority, etc.) can be involved withthe design layout, creating unique coating patterns for the document'score. The coating layout can be held secret, further enhancing thesecurity of the document, while creating obstacles for thecounterfeiter. Changing the coating materials (e.g., the binder) oradditive concentration or adhesive will alter the coating placement andresponse, creating even further obstacles for the counterfeiter and maymake one or more portions of the identification document impossible toengrave with a usable indicia and difficult to duplicate.

Note also that use of the inventive coating described herein may provideat least some of the same advantages (especially in the production ofgrayscale images) previously described in connection with use of theinventive laser enhancing laminate, and they are not repeated here.Further, the lasers previously described in connection with the firstaspect of the invention are similarly usable in this second aspect ofthe invention, and their description is not repeated here.

In another embodiment of the invention (illustrated further herein inconnection with FIG. 8), the inventive laser enhancing additive can bedivided between multiple optically adjacent layers (e.g., a first layerhaving a coating and a laminate, or multiple adjacent laminates (aspreviously described), or a first layer having a coating, a second layerhaving a coating, a third layer having a laminate, a fourth layer havinga coating, etc.). This embodiment can be advantageous for securitypurposes. For example, during laser engraving, the same visible imagecan be engraved in any one or more of the plurality of layers, but,depending on the proportions of the inventive laser additive (and/or itslayer component parts) disposed in each layer, the visible image willnot necessarily look exactly the same in each layer. This can provide avisual effect that is difficult to duplicate.

For example, assume that a layer that is optically “closer” to the laserbeam (e.g., a top layer) has a first concentration of the inventivelaser enhancing additives and a second layer that is optically moredistant (e.g., a layer below the top layer) has a second, higherconcentration of the inventive laser enhancing additives. When these twolayers are laser engraved, the bottom layer will have a visible laserengraved image (e.g., a grayscale image) and the top layer will have aso-called “latent” laser engraved image that can be fainter but stillvisually perceptible to the naked human eye. It also is contemplatedthat the either of the two layers could contain colorants (e.g., bothvisible and non visible (e.g., IR, UV) colorants that furtherdifferentiate between the visible laser engraved image and the latentlaser engraved image.

By “optically adjacent”, it is meant that a laser can pass through fromone layer (e.g., a laminate) to another layer (e.g., a second laminateor a core layer or layer having a coating thereon), such that bothlayers can be laser engraved by the same laser beam at substantially thesame time. Two layers that are optically adjacent need not be literallyadjacent, although they can be. The two layers can be directly adjacent(e.g., two layers that are fused together), or can be separated by amaterial that permits the laser beam to pass therethrough but does notitself necessarily have to react to the laser beam. As an example, foroptical adjacency, the two layers can be separated by an adhesive thatpermits laser light to pass therethrough), or can be separated byanother type of layer (e.g., a thin film layer) that permits laser lightto pass through).

By “dividing the laser enhancing additive”, at least any one or more ofthe following embodiments is included:

(a) the entire additive in the entire desired concentration, e.g. 0.06%by weight, is divided between two optically adjacent layers, for example0.03% in a first layer of laminate and 0.03% in a coating applied to asecond laminate that is optically adjacent to the first laminate, or0.06% by weight in one layer comprising a coating and 0.03% by weight inanother layer comprising a coating); or

(b) a first component of the inventive laser enhancing additive isprovided in a first layer (the “first component” is one of the twocomponents in the inventive laser enhancing additive, either thecomponent comprising at least one of copper iodide, copper potassiumiodide, potassium iodide, sodium iodide, and aluminum iodide (and anycombination thereof) or the component comprising at least one of zincsulfide, barium sulfide, alkyl sulfonate, and thioester (and anycombination thereof)) and a second component of the inventive laserenhancing additive (e.g., the other of the two components in theinventive laser enhancing additive) is provided in another layer that isoptically adjacent to the first layer; or

(c) Each of the constituents of the inventive laser enhancing additive(e.g., copper, potassium, iodine, etc.) can be present in a separatelayer of coating and/or laminate, where the respective layers are eitheradjacent or separated by one or more layers of material (e.g., anotherlaminate or an adhesive) that is transparent to laser radiation. When alaser beam is directed such that it passes through all of the layerscontaining a constituent of the inventive laser enhancing additive, thecombined action of the constituents enable laser engraving to occur inat least one of the respective layers. The constituents also can becombined with one or more other constituents, in different layers, inthis manner. For example, an effective amount of copper iodide andsodium iodide can be present in a coating applied to an article and aneffective amount of zinc sulfide and potassium iodide can be present ina laminate applied over the coating, and an effective amount of aluminumiodide can be present in a coating that is then applied over thatlaminate. This example is not, of course, limiting; those skilled in theart will appreciate that there are many different ways to combine and/orseparate the constituents of the inventive laser enhancing additive intoone or more layers of coatings and/or laminates.

For any of (a), (b), and (c), above, the layers can be, for example:

(i) a plurality of laminates

(ii) a plurality of coatings applied to a given laminate;

(iii) a plurality of coatings applied to a given coating;

(iv) a mixture of a plurality of laminates and/or a plurality ofcoatings

(v) a core layer with a one or more coatings and one or more laminatescoupled to the core layer;

(vi) at least on layer of laminate and at least one layer of coatingapplied over the at least one layer of laminate;

(vii) at least a first laminate with a coating coupled to at least asecond laminate with a coating.

Finally, in another aspect of the invention, we have made the surprisingdiscovery, however, that the LAZERFLAIR pigment can be added to acoating (in a similar manner as adding the above described inventivelaser enhancing additive to a coating) to enable the laser engraving ormarking of grayscale indicia on the article. It is known that theLAZERFLAIR pigment is a laser enhancing additive when added to theactual material to be engraved (see, e.g., the Internet web pagehttp://www.empigments.com/LazerFlair.cfm) such that contrast can beimproved. Our testing has shown, however, that LAZERFLAIR also can beadded to a coating to improve the laser engraving of an article (e.g., acore layer in an identification document) to which the coating isapplied. The LAZERFLAIR additive is available from EM Pigments (EMPigments can be contacted through 7 Skyline Drive, Hawthorne, N.Y. 10532USA)

D.2 Preparation/Manufacture

Embodiments of the inventive coating can be prepared in any customarymanner known to those skilled in the art. For example, in one embodimentwhere the inventive coating comprises an organic polymeric binder,copper potassium iodide, and zinc sulfide, the copper potassium iodideand zinc sulfide can be mixed into the organic polymeric binder duringmixing using a blender; the additive can be ground using, for example, aball mill to reduce particle size.

In another embodiment, the inventive laser enhancing additive can beadded to the coating as part of a masterbatch, such as was describedpreviously for the inventive laser enhancing additives that were addedto laminates. For example, a masterbatch containing 0.03% by weight ofat least one of copper potassium iodide, copper iodide, potassiumiodide, sodium iodide, and aluminum iodide and 0.03% by weight of zincsulfide can be produced and mixed with orgy, each of the two compounds.

Although at least one advantageous embodiment of the invention uses acoating that is a liquid form when applied to the ID document, use of aliquid coating is not necessary. For example, those skilled in the artcan, without undue experimentation, use the inventive laser enhancingadditive in a coating that is applied in a non-liquid form (e.g., solidor powder that liquefies upon heating).

D.3 Illustrative Examples

FIG. 7 is an illustrative cross sectional view of an identificationdocument 10 in accordance with a one embodiment of the second aspect ofthe invention. In the embodiment of FIG. 7, the ID document 10preferably includes a multi-layered structure. For purposes ofillustration, however, the ID document 10 may have a front outwardappearance generally similar to the identification document 10 of FIG.1, although the construction and components of the cross-section shownin FIG. 7 differs from the prior art. In FIG. 7, a core material 50(which for illustrative purposes only is TESLIN), has top surface 67 andbottom surface 69. Although not illustrated in FIG. 7, the core material50 also could be pre printed with one or more indicia, such as variableinformation about the bearer of the identification document 10, by amethod such as color laser Xerography (note that illustrative examplesof printing on the core layer 50 are shown in FIG. 5). A portion of thetop surface 67 of the core layer 50 is coated with an inventive coating70 containing the inventive laser enhancing additive. The inventivecoating 70 could, of course, be applied to the bottom surface 69, ifdesired.

In FIG. 7, the coating 70 can be applied selectively, so that onlyspecific areas of the core material 50 are sensitized for laserengraving. Thus, energy 72 from a laser (not shown) can be specificallydirected at the area of the ID document 10 that contains the inventivecoating 70, to produce indicia 54 l, 54 m on the material that wascoated (which, in this example, is the core layer 50). Such selectiveapplication of the inventive coating 70 can be advantageous, forexample, in the manufacture of identification documents, because theplacement and locations of the coating can be kept secret, to helphinder fraud. For example, counterfeiters may not be able to tell whatinformation on the card has been laser engraved and what has not. Eventhose counterfeiters with access to a laser may not know which areas ofthe identification document are engraveable. Changing any of thecomponents in the identification document, such as the binder, theinventive laser enhancing additive, or the concentration of theinventive laser enhancing additive, can affect the appearance of theidentification document, making detection of a fraud, counterfeit, orforged document perceptible.

Another anti-fraud advantage can be seen in the embodiment of FIG. 7. Ifthe core layer 50 is pre-printed with non-variable or non-personalinformation (such as the name of the issuing authority), then coatedwith the inventive coating 70, the ID document 10 can later bepersonalized (e.g., have variable information, such an image, signature,birthdate, or biometric data) by laser engraving the coated portions ofthe core layer 50 with the variable information. This laser engravingcan even occur if a laminate is applied over the inventive coating 70,if the laminate permits laser energy 72 to pass therethrough to theinventive coating 70 and the core layer 50.

In FIG. 7, a laminate 74 is shown as being disposed on top of theinventive coating 70. The laminate 74 can be applied before or after thecoated areas of the core layer 50 are laser engraved. For example, ifthe laminate 74 is transparent to laser radiation, applying it over theinventive coating 70 will not interfere with the ability of the laserradiation 72 to penetrate through to the inventive coating 70 and thecore layer 50. If, however, the laminate 74 is not transparent to laserradiation 72, it can be applied after the laser engraving of the corematerial 50 has occurred.

The inventive coating 70 can be applied to the surface 67 by any knownmethod (e.g., by offset, flexography, screen-printing, spraying,dipping, immersion, brushing, rolling, masking desired coating areas,etc.). The thickness of the coating 70 is dependent on the article beingcoated, but can range from about 0.01 microns to about 50 microns for IDdocuments such as ID cards. It will be appreciated that other articlesbeing laser engraved may require or use coatings having differentthicknesses.

Although FIG. 7 illustrates that the coating 70 covers only a portion ofthe top surface 67, this is not limiting. The coating 70 can be appliedto any surface, and can, if desired, cover the entire surface.

We have found that the inventive coatings described herein may offer oneor more advantages. For example, using the inventive coatings can enablethe materials being coated to be laser marked or engraved with usablegrayscale images. In addition, using the inventive coatings can enablefaster laser engraving or marking, at lower laser power levels. Also,the inventive coatings can be selectively applied to articles such asidentification documents to increase security and deter fraud. Further,the laser engraving that is possible using the inventive coatings isdurable, abrasion resistant, and environmentally friendly.

D.4 Additional Embodiments of the Second Aspect of the Invention

We anticipate that at least the following combinations, and others likethem, can be useful embodiments of the second aspect of the invention:

1. A coating having laser engraving properties, comprising:

a liquid carrier material; and

an effective amount of a laser enhancing additive, the laser enhancingadditive comprising:

-   -   a first quantity of at least one substance selected from the        group consisting of copper potassium iodide (CuKI₃), copper        iodide (CuI), potassium iodide (CuI), sodium iodide (NaI),        aluminum iodide (AlI); and    -   a second quantity of at least one substance selected from the        group consisting of zinc sulfide (ZnS), barium sulfide (BaS),        alkyl sulfonate, and thioester.

2. The coating recited in 1 above wherein the laser enhancing additiveis present in an amount from about 0.001 to 100 percent by weight basedon the total weight of the composition.

3. The coating recited in 1 above wherein the liquid carrier material issubstantially transparent and the laser enhancing additive is present inan amount from about 0.001 to 0.1 percent by weight based on the totalweight of the composition.

4. The coating recited in 1 above wherein the laser enhancing additiveis present in an amount that is about 0.06 percent by weight based onthe total weight of the composition.

5. The coating recited in 4 above, wherein the first and secondquantities each comprise about 0.03 percent by weight based on the totalweight of the composition.

6. The coating recited in 1 above wherein the first quantity and thesecond quantity are the same.

7. The coating recited in 1 above wherein the first quantity is greaterthan the second quantity.

8. The coating recited in 1 above wherein the first quantity is lessthan the second quantity.

9. The coating recited in 1 above wherein a substrate coated with thecoating is laser engraveable by at least one of a diode pumped Nd:Yaglaser, light pumped Nd:Yag laser, CO₂ laser and excimer laser.

10. The coating recited in 1 above wherein the liquid carrier materialcomprises at least one material selected from the group consisting ofresins, polyesters, polycarbonates, vinyls, acrylates, urethanes, andcellulose based materials, thermosetting material, thermoplastic,polymer, copolymer, polycarbonate, fused polycarbonate, polyester,amorphous polyester, polyolefin, silicon-filled polyolefin, TESLIN,foamed polypropylene film, polyvinyl chloride, polyethylene,thermoplastic resins, engineering thermoplastic, polyurethane,polyamide, polystyrene, expanded polypropylene, polypropylene,acrylonitrile butadiene styrene (ABS), ABS/PC, high impact polystyrene,polyethylene terephthalate (PET), PET-G, PET-F, polybutyleneterephthalate PBT), acetal copolymer (POM), polyetherimide (PEI),polyacrylate, poly(4-vinylpyridine, poly(vinyl acetate),polyacrylonitrile, polymeric liquid crystal resin, polysulfone,polyether nitride, and polycaprolactone.

11. A substrate capable of being laser engraved with a grayscaleindicia, comprising:

a core layer having a first surface; and

a coating applied to at least a first area of the first surface, thecoating comprising:

-   -   a first effective amount of a first compound, the first compound        selected from the group consisting of copper potassium iodide        (CuKI₃), Copper Iodide (CuI), Potassium Iodide (KI), sodium        iodide (NaI), and aluminum iodide (AlI); and    -   a second effective amount of a second compound, the second        compound selected from the group consisting of zinc sulfide        (ZnS), barium sulfide (BaS), alkyl sulfonate, and thioester;

wherein laser energy directed at the first area of the core layer iscapable of forming a grayscale indicium therein.

12. A substrate capable of being laser engraved with a grayscaleindicia, comprising:

a core layer having a first surface;

a first coating applied to at least a first area of the first surface,the first coating comprising an effective amount of a first laserenhancing additive comprising at least one of one of copper potassiumiodide (CuKI₃), copper iodide (CuI), potassium iodide (KI), sodiumiodide (NaI), and aluminum iodide (AlI); and

a second coating applied to at least a second area of the core layer,the second coating comprising an effective amount of a second laserenhancing additive, the second laser enhancing additive selected fromthe group consisting of zinc sulfide (ZnS), barium sulfide (BaS), alkylsulfonate, and thioester;

the first and second areas at least partially overlapping on the corelayer to define a third area on the core layer;

wherein laser energy directed at the third area of the core layer iscapable of forming a grayscale indicium therein.

13. A method of producing an identification document, comprising:

providing a core including a top surface and a bottom surface; and

coating at least a portion of the top surface with a laser sensitiveadditive, the laser sensitive additive comprising:

-   -   an effective amount of at least one of one of copper potassium        iodide (CuKI₃), Copper Iodide (CuI) potassium iodide (KI),        sodium iodide (NaI), and aluminum iodide (AlI); and    -   an effective amount of at least one of zinc sulfide (ZnS),        barium sulfide

(BaS), alkyl sulfonate, and thioester.

14. The method recited in 13 above further comprising laminating atleast the top surface of the core with a laminate.

15. The method recited in 13 above further comprising directing a laserbeam so that it passes through at least a portion of the coating andreaches the core layer to form a grayscale indicium on the core layer.

16. The method recited in 13 above, wherein the core comprises at leastone of TESLIN, polycarbonate, polyester, and polyvinyl chloride.

17. The method of recited in 13 above wherein the coating comprisesCopper Iodide (CuI) potassium iodide (KI), sodium iodide (NaI), andaluminum iodide (AlI).

E. THIRD ASPECT OF THE INVENTION

In a third aspect of the invention, the invention utilizes the inventivelaser enhancing laminate (or components thereof) in more than one layeron the identification document. Several embodiments of this aspectalready have been presented above in the first and second aspects of theinvention. Still another embodiment of this aspect is provided below.

FIG. 8 is an illustrative cross sectional view of an identificationdocument in accordance with a second embodiment of the second aspect ofthe invention. In the embodiment of FIG. 8, the ID document 10preferably includes a multi-layered structure, and the inventive laserenhancing additive is divided between two optically adjacent layers, aspreviously described. For purposes of illustration, however, the IDdocument 10 may have a front outward appearance generally similar to theidentification document 10 of FIG. 1, although the construction andcomponents of the cross-section shown in FIG. 8 differs from the priorart. In the embodiment of FIG. 8 a first portion of the inventive laserenhancing additive is disposed in a first coating 76 and a secondportion of the inventive laser enhancing additive is disposed in amiddle laminate 78 applied over the first coating 76. An overlaminate 74is applied over the middle laminate 78. The first coating 76 is appliedto the core layer 50, which in FIG. 8 is made from an opaque whitematerial, such as TESLIN or polycarbonate.

In the embodiment of FIG. 8, the first coating 76 contains a firsteffective amount of at least one of copper potassium iodide (CuKI₃),copper iodide (CuI), potassium iodide (KI), sodium iodide (NaI), andaluminum iodide (AlI), and the middle laminate 78 contains a secondeffective amount of at least one of the following: zinc sulfide (ZnS),barium sulfide (BaS), alkyl sulfonate and thioester. The first effectiveamount is greater than the second effective amount, in this embodiment.The first coating 76 and middle laminate 78 are constructed and arrangedso that the laser radiation 72 can pass through both the first coating76 and middle laminate 78 to form indicia 54 n, 54 o and latent indicia82, 84 on the ID document 10. Although not apparent in the crosssectional view of FIG. 8, our testing has shown that the indicia 54 l,54 m formed on the core layer 50 can be a usable grayscale image (byusable, it is at least meant that image can be used for securitypurposes, such as identification or authentication). As previouslydescribed, the latent indicia 82, 84 can comprise lighter or fainter(but still visible) version of the indicia 54 n, 54 o.

The latent indicia 82, 84 can be advantageous as a security featurebecause a counterfeiter may remove the middle laminate 78 in an attemptto alter information in the middle laminate 78, but the information willstill be present on the core layer 50 that has the first coating 76.Similarly, a counterfeiter may attempt to remove then replace the middlelaminate 78, in order to alter information on the core layer 78, but thelatent indicia 82, 84 will still be present and visible in the middlelaminate 78. As those skilled in the art will appreciate, the type andplacement of an indicia is formed on the core layer 50 depends on theparticular type of laser used the manner in which the laser is used(e.g., pumped), and the duration of the application of laser energy.

It should be understood that although the example of FIG. 8 shows thatthe first coating 76 contains the effective amount of at least one ofcopper potassium iodide (CuKI₃), copper iodide (CuI), potassium iodide(KI), sodium iodide (NaI), and aluminum iodide (AlI), and the middlelaminate 78 contains the effective amount of at least one of zincsulfide (ZnS), barium sulfide (BaS), alkyl sulfonate and thioester, thepositions of the two compounds in the respective first and second layerscould be reversed. That is, the first coating 67 could contain theeffective amount of at least one of zinc sulfide (ZnS), barium sulfide(BaS), alkyl sulfonate and thioester, and the second coating 78 couldcontain the effective amount of copper potassium iodide (CuKI₃), copperiodide (CuI), potassium iodide (Kr), sodium iodide (NaI), and aluminumiodide (AlI).

CONCLUDING REMARKS

Depending on the availability of lasers, identification documentsmanufactured in accordance with the invention can be produced in bothover the counter and central issue environments. One example of aprinting device that may be usable for at least some over the counterembodiments of the invention is the DATACARD DCL30 Desktop Card LaserPersonalization System, available from Datacard Group of Minnetonka,Minn.

In one embodiment, following lamination and laser engraving, the IDdocument 10 is cooled and is cut (e.g., by die-cutting) to apredetermined size. In at least one embodiment, however, the substrateand laminate can be sized such that cutting the laminated printedsubstrate is not necessary.

The identification document 10 of the invention may be manufactured inany desired size. For example, identification documents can range insize from standard business card size (47.6.times.85.7 mm) up toidentification booklet documents (127.times.177.8 mm), and can havethicknesses in the range of from about 0.3 to about 1.3 mm. At leastsome identification documents produced in accordance with embodiments ofthe invention conform to all the requirements of ISO 7810, 1985 and willthus be of the CR-80 size, 85.47-85.73 mm wide, 53.92-54.03 mm high and0.69-0.84 mm thick. The corners of such CR-80 documents are rounded witha radius of 2.88-3.48 mm.

In addition, while the preferred embodiments have been described withreference to cyan, magenta and yellow dyes, the present invention is notso limited. The present invention can include addition color,alternative color schemes and even spot colors. Also, while the presentinvention has been described with reference to NIR, the inventivetechnique can be expanded to include dyes responsive in the ultra-violetspectrum and other IR ranges.

Further, while some of the examples above are disclosed with specificcore components (e.g., TESLIN), we note that our inventive compositions,methods, articles, features, and processes can be applied to othercore-based identification documents as well, including those documentsmanufactured from other materials. For example, where an embodiment hasshown polycarbonate or polyester as an example over-laminate, thoseskilled in the art will appreciate that many other over laminatematerials can be used as well.

We specifically contemplate that embodiments of the invention describedherein will be usable and can be combined with at least some of the cardstructures disclosed in many of our previous patent applications,including at least commonly assigned patent application Ser. No.60/471,429 entitled “Identification Document” (especially cardstructures that include polycarbonate) and in commonly assigned patentapplication Ser. No. 60/500,204, entitled “Identification Document withOptical Memory and Related Method of Manufacture”. The contents of thesepatent documents are incorporated by reference in their entirety.

We also specifically contemplate that embodiments of the inventiondescribed herein will be usable and can be combined with the teachingsof commonly assigned patent application Ser. No. 10/330,034, entitled“Systems, Compositions, and Methods for Full Color Laser Engraving of IDDocuments”.

We further specifically contemplate that embodiments of the inventiondescribed herein will be usable and can be combined with the teachingsof a commonly assigned patent application filed on Sep. 15, 2003,entitled “Enhanced Shadow Reduction System and Related Technologies forDigital Image Capture”, Attorney Docket No. P0883D.

The inventive coatings described herein may be used to sensitize othercore components as well. Also, we note that the coating can be appliedto both a document core and to an over-laminate, and that the laserengraving can be preformed in both (or either) the core andover-laminate.

To provide a comprehensive disclosure without unduly lengthening thespecification, applicants herein incorporate by reference each of thepatent documents referenced previously, along with U.S. Pat. Nos.6,022,905, 5,298,922, 5,294,774, 4,652,722, 5,824,715 and 5,633,119, andU.S. patent Ser. Nos. 09/747,735 (filed Dec. 22, 2000) and 09/969,200(filed Oct. 2, 2001).

Having described and illustrated the principles of the technology withreference to specific implementations, it will be recognized that thetechnology can be implemented in many other, different, forms.

Although certain words, languages, phrases, terminology, and productbrands have been used herein to describe the various features of theembodiments of the invention, their use is not intended as limiting. Useof a given word, phrase, language, terminology, or product brand isintended to include all grammatical, literal, scientific, technical, andfunctional equivalents. The terminology used herein is for the purposeof description and not limitation.

The technology disclosed herein can be used in combination with othertechnologies. Examples include the technology detailed in the followingapplications, the disclosures of which are incorporated herein byreference: 09/747,735 (filed Dec. 22, 2000), 09/969,200 (filed Oct. 2,2001). Also, instead of ID documents, the inventive techniques can beemployed with product tags, product packaging, business cards, bags,charts, maps, labels, etc., etc., particularly those items includingengraving of an over-laminate structure. The term ID document is broadlydefined herein to include these tags, labels, packaging, cards, etc. Inaddition, while some of the examples above are disclosed with specificcore components, it is noted that-laminates can be sensitized for usewith other core components.

To provide a comprehensive disclosure without unduly lengthening thespecification, applicant hereby incorporates by reference each of thepatents and patent applications referenced above.

The particular combinations of elements and features in theabove-detailed embodiments are exemplary only; the interchanging andsubstitution of these teachings with other teachings in this and theincorporated-by-reference patents/applications are also expresslycontemplated. As those skilled in the art will recognize, variations,modifications, and other implementations of what is described herein canoccur to those of ordinary skill in the art without departing from thespirit and the scope of the invention as claimed. Accordingly, theforegoing description is by way of example only and is not intended aslimiting. The invention's scope is defined in the following claims andthe equivalents thereto.

1. (canceled)
 2. A multi-layered identification document comprising: acore material layer; a first laminate over the core material layer; asecond laminate over the first laminate; a laser sensitizing additive tothe first laminate including a first quantity of at least one of copperpotassium iodide (CuKI₃), Copper Iodide (CuT), potassium iodide (KI),sodium iodide (NaI) and aluminum iodide (AlI); a laser sensitizingadditive to the second laminate including a second quantity of at leastone substance related from the group comprising of zinc sulfide (ZnS),barium sulfide (BaS), alkyl sulfonate, and thioester.
 3. Theidentification document of claim 2, further comprising a layer ofmaterial between the first and second laminates, the layer of materialbeing transparent to laser light radiation.
 4. The identificationdocument of claim 2, wherein the core material layer includes a titaniumdioxide (TiO₂) filled polycarbonate film.
 5. The identification documentof claim 2, wherein the core material layer includes preprintedinformation thereon.
 6. The identification document of claim 2, whereinthe core material layer and the first and second laminate are fusedtogether, such fused materials deterring delamination attempts.
 7. Theidentification document of claim 2, wherein the identification documentbears a first indicium thereon, the first indicium obtained by exposingthe laser sensitizing additive to a laser beam.
 8. The identificationdocument of claim 7, wherein the indicium comprises at least one of: agray scale image, photograph, text, tactile text, graphic information,security pattern, security indicia, and digital watermark.
 9. Theidentification document of claim 7, wherein the first indicium comprisesvariable information.
 10. A process of making an identification documentcomprising: providing a core layer material; overlying a first laminateover the core material, wherein the first laminate includes a firstlaser sensitizing material having first quantity of at least one ofcopper potassium iodide (CuKI), copper iodide (CuI), potassium iodide(KI), sodium iodide (NaI) and aluminum iodide (AlI); overlying the firstlaminate with a second laminate, wherein the second laminate includes asecond laser sensitizing material having a second quantity of at leastone substance selected from the group consisting of zinc sulfide (ZnS),barium sulfide (BaS), alkyl sulfonate and thioester; and fusing togetherthe core laser material, the first laminate and the second laminateusing at least one of heat and pressure.
 11. The method of claim 10,further comprising the step of providing preprinted information on thecore material layer prior to overlying the core material layer with thefirst laminate.
 12. The method of claim 10, wherein the identificationdocument bears a first indicium thereon, the first indicium obtained byexposing the laser sensitizing additive to a laser beam.
 13. The methodof claim 12, wherein the first indicium comprises variable information.